1) Problem #PRAFTAF "PRAFTAF - 164336 - The governor's of..." |
A)
The governor's office is conducting a survey on class sizes in high schools within the state of Massachusetts. By doing this, the governor hopes to make a comparison and correlation with class sizes and academic performance. A simple random sample of the number of students in a class is conducted for 8 high schools, the results being: 26 31 23 22 11 22 14 31 What conditions must be satisfied in order to make intferences about m, the mean number of students in each class? Check all that apply. |
Multiple Choice:
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B)
Construct a 95% confidence interval for m. Use the Inference Toolbox. |
Multiple Choice:
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Hints: |
t* = 2.365 x'bar = 22.5 s = 7.19 |
2) Problem #PRAFTBF "PRAFTBF - 164367 - Which of the foll..." |
Which of the following statements is true? |
Multiple Choice:
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3) Problem #PRAFTBK "PRAFTBK - 164371 - A study was condu..." |
A)
A study was conducted on the time it took mice to run through a certain maze. Each mouse was run through two trials. The changes in the times for the 34 mice are shown below: 2 5 7 -2 2 7 4 1 0 7 3 4 3 4 9 4 5 2 9 6 0 3 6 -1 3 4 6 7 -2 7 -3 3 4 4 Display the data and summarize the distribution. |
Multiple Choice:
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B)
Give a 95% confidence interval for the mean improvement in reasoning scores. |
Multiple Choice:
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Hints: |
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4) Problem #PRAFS28 "PRAFS28 - 164112 - A recent study of..." |
A)
A recent study of 32 high-school students showed that the mean amount of pairs of shoes they own is 9. The standard deviation of the sample is 3. Find the 90% confidence interval of the true mean. What is the lower limit of your confidence interval? Answer as a decimal rounded to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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B)
What is the upper limit of you confidence interval? Answer as a decimal rounded to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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5) Problem #PRAFS3P "PRAFS3P - 164126 - Another recent st..." |
A)
Another recent study of 51 local soccer fans showed that the mean amount of number of games they attended last season was 11 games. The standard deviation of the sample was 4 games. Find the 90% confidence interval of the true mean. What is the lower limit of your confidence interval? Answer as a decimal rounded to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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B)
What is the upper limit of your confidence interval? Answer as a decimal rounded to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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6) Problem #PRAFS3Q "PRAFS3Q - 164127 - When solving prob..." |
When solving problems involving confidence intervals, which table must you use in order to get the right answer? |
Multiple Choice:
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7) Problem #PRAFS4A "PRAFS4A - Confidence Intervals 5" |
Nine hundred college freshmen in Massachusetts were randomly selected for a state-wide survey. Among survey participants, the mean GPA was 2.7, and the standard deviation was 0.4. What is the margin of error, assuming a 95% confidence level? (A) 0.013
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Algebraic Expression:
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Hints: |
To compute the margin of error, we need to find the critical value and the standard error of the mean. To find the critical value, we take the following steps: Firstly, determine alpha: α = 1 - (confidence level / 100) = 1 - 0.95 = 0.05 Secondly, find the p*: p* = 1 - α/2 = 1 - 0.05/2 = 0.975 Thirdly, find the z* score on a z-table. We find that the critical value is 1.96. |
Next, we find the standard error of the mean, using the following equation: SEx = s / sqrt( n ) = 0.4 / sqrt( 900 ) = 0.4 / 30 = 0.013 And finally, we compute the margin of error (ME). ME = Critical value x Standard error = 1.96 * 0.013 = 0.025 |
8) Problem #PRAFSCH "PRAFSCH - Confidence Intervals 1" |
Suppose 19 billionaires in the United States are surveyed about their average annual donations to charity, and the results are approximately normally distributed. The mean is 15 percent of their annual income, and the standard deviation is 5 percent. What is the 95% confidence interval for the mean percent. |
Algebraic Expression:
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Hints: |
Use t as opposed to z* for this problem. |
Use the formula: 15 tc 5 / Since n = 19, there are 18 degrees of freedom. Using the t table, you can see that: tc = 2.10 The margin of error is 2.10 (5) / = 2.4 We can conclude with 95% confidence that the millionaires donate between 12.6% and 17.4% of their income to charity. |
(____, ____) |
9) Problem #PRAFS3Z "PRAFS3Z - Confidence Interval 3" |
A sample of 61 high school students were asked how many hours a week they sleep. The sample produced a mean of 48 minutes, for which S=14 minutes. Compute a 95 percent confidence interval for this data.
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Algebraic Expression:
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Hints: |
The standard error of the mean is 1.807392228. t=2.000. |
Confidence Interval at 95 percent: 43.5 < population mean < 52.5. This tells us that we can be 95 percent certain that the population mean for the number of hours a high school student receives per week is somewhere between 43.5 and 52.5. |
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10) Problem #PRAFSCJ "PRAFSCJ - Confidence Intervals 2" |
Amanda measured the heights of all of her china dolls. Assume her collection is a SRS. The heights of her 24 dolls are listed below:
Compute a 95 percent confidence interval. What does this tell Amanda about the height of china dolls? |
Algebraic Expression:
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Hints: |
Input the numbers into your calculator. It should tell you that
Mean = 10.92 |
Confidence Interval at 95 percent: 8.50 < population mean < 13.3 Amanda can be 95 percent sure that the actual population mean for the height of china dolls is somewhere between 8.5 inches and 13.3 inches. There is a 5 percent chance that the population mean does not lie within that interval. |
(___, ____) |
11) Problem #PRAFS3X "PRAFS3X - 164134 - A survey was sent..." |
A survey was sent to 560 gym members asking about their satisfaction with the gym. 135 members returned the survey. The mean response was x-bar = 5.396. Assume that the population standard deviation was σ = 1.75. Determine a 90% confidence interval for the mean of the population. Round to three decimal places. |
Algebraic Expression:
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Hints: |
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σ = 1.75 n = 135 Z* = 1.660 |
12) Problem #PRAFS4F "PRAFS4F - 164150 - Of these options,..." |
Of these options, which does NOT occur when the margin of error of a confidence interval gets smaller? |
Multiple Choice:
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13) Problem #PRAFS4M "PRAFS4M - 164155 - If a there is a m..." |
If a there is a margin of error of 3 percentage points for a 95% confidence interval, what does "95% confidence" mean? |
Multiple Choice:
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14) Problem #PRAFS4S "PRAFS4S - 164160 - These are measure..." |
These are measurements (in inches) of heights of buildings around Boston. 224.120 224.001 224.017 223.982 223.989 223.961 223.960 224.089 223.987 223.976 223.902 223.980 224.098 224.057 223.913 223.999 The standard deviation is σ = .060. The mean is 224. |
Algebraic Expression:
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15) Problem #PRAFTUD "PRAFTUD - 164861 - A study is taken ..." |
A)
A study is taken among teenagers to find the average number of shoes an individual owns. In the data graph below, X represents the number of pairs of shoes and the frequency representes the number of individuals with the corresponding number of pairs. Considering a 90% confidence interval, what is the lower bound for the data? Round answers to the nearest hundredth.
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Exact Match (case sensitive):
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B)
Using the same confidence interval of 90% and the same data, please find the upper bound. Round answers to the nearest hundredth.
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Exact Match (case sensitive):
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C)
A sample is taken of a small class at BLS of how many AP classes each student takes. The results of the survery are shown below. The X represents the number of AP courses and the frequency represents the number of students with that corresponding number. Using a 95% confidence interval, pelase find the lower bound. Round to the nearest hundredth.
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Exact Match (case sensitive):
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D)
Using the same data table from the previous problem and still using a 95% confidence interval, please find the upper bound. Round to the nearest hundredth.
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Exact Match (case sensitive):
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E)
Another survey at BLS was conducted to see how many textbooks each student had in their locker. The table below shows the results of the survey. The X represents the number of textbooks, and the frequency represents the number of students with that many textbooks. Using a 99% confidence interval please find the population mean range. Round answer to the nearest hundredth and use a (number, number) format in your answer.
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Exact Match (case sensitive):
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16) Problem #PRAFSW7 "PRAFSW7 - 696969 - DIELAWN" |
A)
A simple random sample (SRS) of 85 students from Mr. Simoneau's class aresurveyed . The students responses show that they have an awesome learning experience in class with a mean of 5 days a week. Assume the distribution for the population is non-normal, and σ = 0 days. Let's calculate the 95% confidence interval of the mean number of days of awesomeness per week in Mr.Simoneau's class. First, what is the number that represents the point estimate for this problem? |
Algebraic Expression:
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Hints: |
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B)
What is z* for a 95% confidence interval? |
Algebraic Expression:
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Hints: |
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C)
Let's now calculate the margin of error. What is the margin of error for this problem? Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
m = z* (standard deviation/ sqrt of n) |
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D)
What is the 95% confidence interval for this problem? Round to the nearest hundredth and write in the form ( ___ , ___ ) |
Algebraic Expression:
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Hints: |
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E)
Now calculate the 99% confidence interval for this problem, round to the nearest hundredths and use the same methods. |
Algebraic Expression:
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Hints: |
Answer: (5,5) |
17) Problem #PRAFSZ8 "PRAFSZ8 - CH10" |
H0 is the null hypothesis, and is usually a statement of "no loss." Ha is known as the ________ and is a statement saying "____________." |
Multiple Choice:
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18) Problem #PRAFS2B "PRAFS2B - equation ch10" |
After plugging in mu, x-bar and sigma in this equation in order to solve z, z= x bar - mu / sigma What is the next step? |
Multiple Choice:
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19) Problem #PRAFS2K "PRAFS2K - nulll CH10" |
Ho: μ = 100 Ha: μ ≠ 100 In this situation you _______________. Ho: μ = 100 Ha: μ < 100 In this situation you ________________. |
Multiple Choice:
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20) Problem #PRAFS2T "PRAFS2T - 3_ch10" |
Conditions for constructing a ___________ for the mean.
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Exact Match (case sensitive):
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Hints: |
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21) Problem #PRAFS5M "PRAFS5M - Problem #164186" |
A survey found that out of 200 people, 168 said they had eaten at an Indian Restaurant three or more times a month. Find the 90% confidence interval of the population of people that eat at an Indian Restaurant three or more times an hour. What is the lower limit of your confidence interval? Answer as a decimal, and round answer to the nearest hundredth. |
Algebraic Expression:
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22) Problem #PRAFS5U "PRAFS5U - 164193 - The proportion of..." |
The proportion of students going to church is around 11%. A random sample of 450 students from a wide geographic area indicated 55 went to church. Estimate the true proportion of students attending private schools witha 95% confidence. What is the lower limit of your confidence interval? Answer as a decimal and round answer to the nearest hundredth. |
Algebraic Expression:
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23) Problem #PRAFS56 "PRAFS56 - 164203 - A teacher wants t..." |
A teacher wants to estimate the proportion of students who are under stress. She wants to be 90% confident that her estimate is within 5% of the true proportion. How large a same should be taken if in a sample of 300, 30 were under stress? |
Algebraic Expression:
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24) Problem #PRAFTUA "PRAFTUA - 164858 - In a statistics c..." |
In a statistics class of 30 students, the average numerical grade is a 79. The normal distribution of all statistics students has a standard deviation of 4.5. What is the lower wing of the range mu with a 95% confidence? Answer as a decimal rounded to the nearest thousanth. |
Algebraic Expression:
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Hints: |
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Z* = 1.96 sigma = 4.5 n = 30 |
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25) Problem #PRAFTUQ "PRAFTUQ - 164871 - A college bound s..." |
A college bound student was curious as to how many high school graduates immediately attended college. She surveyed 100 graduates and of them 70 of them claimed to have plans of starting college in the fall. The standard deviation of the normal distribution of all high school graduates is 10. What would the margin of error be with 95% confidence? Answer as a decimal rounded to the nearest thousanth. |
Algebraic Expression:
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Hints: |
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sigma = 10 n = 100 |
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26) Problem #PRAFTUG "PRAFTUG - 164864 - John had a box of..." |
John had a box of crayons and he liked taking notes best with the blue one. The probability that John grabbed a blue crayon from the box on any given day was .30. If he reaches into the box every school day for five weeks (25 days), what is the upper wing of the mu range with a 90% confidence? Answer as a decimal rounded to the nearest hundreth. |
Algebraic Expression:
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Hints: |
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q.hat = .70 Z* =1.645 n = 25 |
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27) Problem #PRAFTUU "PRAFTUU - 164875 - A sample of stude..." |
A)
A sample of students from an introductory psychology class were polled regarding the number of hours they spent studying for the last exam. All students anonymously submitted the number of hours on a 3 by 5 card. There were 24 individuals in the one section of the course polled. The data was used to make inferences regarding the other students taking the course. There data are below:
Compute a 95 percent confidence interval. What is the mean of the data above? |
Algebraic Expression:
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Hints: |
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B)
According to the data listed above, what is the standard deviation of the data set? Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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C)
Does this problem fail to reject or reject the null hypothesis? |
Multiple Choice:
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28) Problem #PRAFTUV "PRAFTUV - 164876 - Suppose we want t..." |
Suppose we want to estimate the average weight of an adult male in Dekalb County, Georgia. We draw a random sample of 1,000 men from a population of 1,000,000 men and weigh them. We find that the average man in our sample weighs 180 pounds, and the standard deviation of the sample is 30 pounds. What is the 95% confidence interval. |
Algebraic Expression:
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Hints: |
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SE = s / sqrt( n ) = 30 / sqrt(1000) = 30/31.62 = 0.95 Find the z-score. Because the sample size is large, a z score analysis produces the same result - a critical value equal to 1.96. |
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29) Problem #PRAFSZ3 "PRAFSZ3 - 164076 - A recent poll of ..." |
A recent poll of 2,000 Americans found that 65% believed the Academy Award for Best Picture should have been awarded to 127 Hours. The margin of error was reported as +/- 2 percentage points for 95% confidence. What is the 95% confidence interval for Americans who believe 127 Hours was the best movie made in 2010? |
Multiple Choice:
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30) Problem #PRAFSZ4 "PRAFSZ4 - 164077 - A recent study re..." |
A)
A recent study recorded the heights of 20 6-year-old girls in centimeters(the results are as follow): 100, 102, 100, 102, 104, 106, 106, 105, 104, 99, 103, 103, 103, 106, 107, 109, 100, 101, 100, 99 What is the mean of the sample (aka x-bar)? Round to the nearest hundredth. |
Algebraic Expression:
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B)
What is the standard deviation of the sample? Round to the nearest hundredth. |
Algebraic Expression:
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C)
What is the 95% confidence interval for the population of 6-year-old girls? |
Multiple Choice:
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31) Problem #PRAFSZ7 "PRAFSZ7 - 164080 - As n gets larger,..." |
A)
As n gets larger, does the margin of error increase or decrease for any fixed confidence level? |
Multiple Choice:
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B)
As z-star gets smaller, does the confidence level get smaller or larger? |
Multiple Choice:
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32) Problem #PRAFTSW "PRAFTSW - 164815 - Coldstone creamer..." |
A)
Coldstone creamery wants to know if they should build a new establishment in Cambridge, Ma. However they aren't sure how many people would eat their ice cream as opposed to those who would eat Ben and Jerrys. They decided to take a poll of 500 people asking them how many times would they eat Coldstone in a month is they opened one in the Cambridge area. X-bar was 4 and σ was .6. Find the 90% confidence interval. |
Multiple Choice:
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Hints: |
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B)
Find the 95% Confidence Interval. |
Multiple Choice:
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C)
Find the 99% confidence interval. |
Multiple Choice:
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33) Problem #PRAFT9A "PRAFT9A - 165261 - Evelyn was readin..." |
A)
Evelyn was reading an article in the paperr on how many female teen drivers admit to still texting or talking on the phone even if it is against the law. The article stated that the standard deviation was 77 and the margin of error was 15.6, and a z*of 95% but she didn't know the sample size? Use the information provided to find the sample size used for this study. Round to the nearest whole number. |
Multiple Choice:
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Hints: |
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B)
The following week Evelyn was also reading the paper and then she came upon the same study except for male teen drivers. They stated a standard deviation of 82, a margin of error of 12.3, and a z* of 95%; but once again they were lacking the sample size and so that was up to her to solve. Using the information provided, find the sample size used for this study. Round to the nearest whole number. |
Multiple Choice:
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34) Problem #PRAFS5Y "PRAFS5Y - 164197 - What is the 90% c..." |
What is the 90% confidence interval for a sample size of 23? |
Multiple Choice:
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35) Problem #PRAFS49 "PRAFS49 - 164175 - The Globe intervi..." |
A)
The Globe interviewed 1000 women asking whether or not they would enjoy living in Downtown Boston. The poll found that 56% of the women said that would not enjoy it. The poll says that the margin of error is plus and minus 4 percentage points for 95% confidence in its conclusions. What is the 95% confidence interval for the percent of women who say that they would not enjoy living in Downtown Boston? |
Multiple Choice:
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B)
What does "95% confidence" mean in this case? |
Multiple Choice:
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36) Problem #PRAFS6C "PRAFS6C - 164209 - The New York Time..." |
The New York Times wanted to estimate the average weight of men in New York City. They ask 1000 men from a population of 1,000,000. They found that the average weight was 180 pounds with a standard deviation of this sample is 30 pounds. What is the 95% confidence interval? |
Multiple Choice:
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37) Problem #PRAFS54 "PRAFS54 - 164201 - A sample of stude..." |
A sample of students in an AP Stats class were polled and asked how many hours they studied for the last exam. The following are the number: 4.5, 22, 7, 14.5, 9, 9, 3.5, 8, 11, 7.5, 18, 20, 7.5, 9, 10.5, 15, 19, 2.5, 5, 9, 8.5, 14, 20,8. Find the 95% confidence interval. Write the answer exactly as it is shown, without rounding. |
Multiple Choice:
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38) Problem #PRAFS6U "PRAFS6U - 164224 - The weight of a s..." |
A)
The weight of a soda can was tested repeatedly. The mean weight of a soda can is 15 grams. The weight of a soda can is normally distributed. The standard deviation of the soda can is .13 grams. What is x-bar in this situation? |
Algebraic Expression:
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B)
What is the margin of error for the weight of the soda can if it was weight 16 times with a confidence interval of 95%? Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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=7.35 |
C)
Find the lower limit of the confidence interval. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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D)
Find the upper limit of the confidence interval. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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39) Problem #PRAFS62 "PRAFS62 - 164230 - The following dat..." |
A)
The following data set shows the different heights of fern plants in inches: 10, 23, 34, 15, 21, 30 Find the mean of the sample. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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B)
Find the standard deviation of the sample. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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C)
Find the margin of error with a confidence level of 90%. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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=7.39 |
D)
Find the lower bound. Round to the nearest hundredth. |
Algebraic Expression:
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E)
Find the upper bound. Round to the nearest hundredth. |
Algebraic Expression:
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40) Problem #PRAFS6V "PRAFS6V - 164225 - A battery company..." |
A)
A battery company is producing new batteries that will last longer. The mean of the life of a battery they produce is usually 110 hours. The standard deviation of the population is 12. What is x-bar in this situation? |
Algebraic Expression:
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B)
Find the margin of error if the confidence interval was 99% and the sample size was 36. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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C)
Find the lower bound of the confidence interval. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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D)
Find the upper bound of the confidence interval. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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41) Problem #PRAFS63 "PRAFS63 - 164231 - A farmer is growi..." |
A)
A farmer is growing apple trees in his yard. The total amount of apples from all the trees is 364. The mean of the population is 102 apples per tree. The farmer takes 5 sample trees. What is the mean of the sample? |
Algebraic Expression:
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B)
Find the margin of error with a confidence level of 60%. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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C)
Find the lower bound. Round to the nearest hundredth. |
Algebraic Expression:
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D)
Find the upper bound. Round to the nearest hundredth. |
Algebraic Expression:
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42) Problem #PRAFSVG "PRAFSVG - confidence interval 2" |
A Sample of 300 tomato feilds were collected and examined. The mean number of bushels per acre was 120.5 with a standard deviation of 25. Construct a 90% confidence interval for this data set. (Round to the nearest hundreths) **What is the lower bound of the confidence interval? |
Algebraic Expression:
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43) Problem #PRAFSVH "PRAFSVH - confidence interval 3" |
A Sample of 300 tomato feilds were collected and examined. The mean number of bushels per acre was 120.5 with a standard deviation of 25. Construct a 90% confidence interval for this data set. (Round to the nearest hundreths) **What is the upper bound of the confidence interval? |
Algebraic Expression:
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44) Problem #PRAFSVJ "PRAFSVJ - confidence interval 4" |
The ACT would like to create an accurate representation of students scores within plus or minus 10 (margina of error) with a 90% confidence level. The standard deviation of this data is 20. Find the sample size needed inorder to make this statement true. (Round to the nearest whole number) |
Algebraic Expression:
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45) Problem #PRAFS2C "PRAFS2C - 164085 - U.S. News and Wor..." |
U.S. News and World Report conducted a poll on the approval rating of the president. They randomly selected 1000 people from the United States and found that 53% approved of the president. Knowing there is a margin of error of plus/minus 2 percentage points for the 95% confidence in the magazine's findings, what is the 95% confidence interval for the percent of people who approve of the president? |
Algebraic Expression:
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Hints: |
The answer is 51% to 55% |
46) Problem #PRAFS2F "PRAFS2F - 164088 - A jewelry maker m..." |
A jewelry maker measured the lengths of 6 of her necklaces and observes the lengths to be (in centimeters) 102.5, 101.7, 103.1, 100.9, 100.5, and 102.2. The sample mean is 101.82. If she knows the standard deviation is 1.2 cm, what is the confidence interval for the population mean at a 95% confidence level? Round your answer to the nearest hundredth place. |
Algebraic Expression:
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Hints: |
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47) Problem #PRAFS48 "PRAFS48 - 164174 - A boss conducts a..." |
A boss conducts a survey of 19 workers to find out what percent of their income they spend on food. He discovers the mean percent is 15 with a standard deviation of 5 percent. Find a 95% confidence interval for the mean percent. Assume that the distribution of all food percents is approximately normal. |
Algebraic Expression:
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Hints: |
t=2.10 margin of error= plus/minus 2.10 (5)/ sqrt 19 we conclude with 95% confidence that the workers spend between 12.6% and 17.4% of their income on food |
48) Problem #PRAFS4P "PRAFS4P - 164157 - The weight of eve..." |
The weight of every hockey stick is carefully measured in grams. The standard deviation is 40 grams. An SRS of 30 sticks is taken with x-bar equaling 300 grams. Construct a 90% confidence interval for the mean weight of all the hockey sticks prodcued. |
Exact Match (case sensitive):
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Hints: |
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49) Problem #PRAFS4Y "PRAFS4Y - 164166 - An SRS of 150 bas..." |
An SRS of 150 baseball players was taken. They were asked how long they had been on their current team. The average ammount of time each player had been on that current team was 2 years. Give a 95% confidence interval for the mean number of years baseball players have been on their current team for. (the standard deviation of time with a team for all players is 2.5 years) |
Exact Match (case sensitive):
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Hints: |
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50) Problem #PRAFS44 "PRAFS44 - 164170 - The hockey stick ..." |
The hockey stick company wants a report of the mean weight to be within +/- 4 grams with 95% confidence. How lareg a sample of hockey sticks should be measured to meet this request? (standard deviation is 40 grams) |
Multiple Choice:
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51) Problem #PRAFTUP "PRAFTUP - Number 1" |
What are two conditions for creating a confidence interval for the mean μ? |
Check All That Apply:
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52) Problem #PRAFTU3 "PRAFTU3 - Number 3" |
What happens to the variance of a distribution when the sample size decreases and everything else stays the same? |
Multiple Choice:
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53) Problem #PRAFTU4 "PRAFTU4 - Number 4" |
A)
Best Buy sells hundreds of different laptops. A sample group was taken for some studies nd the group averaged to having 4.00 Gb of RAM memory, with a standard deviation of 0.50 Gb. The size of the sample that was taken was 100 laptops. Calculate the 90% confidence interval of RAM for a laptop. What is the lower limit of the confidence interval? Round to hte nearest hundredth if necessary. |
Algebraic Expression:
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B)
What is the upper limit of the confidence interval? Round to the nearest hundredth if necessary. |
Algebraic Expression:
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54) Problem #PRAFTU9 "PRAFTU9 - 164888 - What does it mean..." |
What does it mean to have a 95% confidence interval? |
Multiple Choice:
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55) Problem #PRAFS9A "PRAFS9A - 164300 - As the standard d..." |
As the standard deviation increases, the margin of error increases. |
Multiple Choice:
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56) Problem #PRAFS89 "PRAFS89 - 164299 - As N increases th..." |
As N increases the marginal of error increases. |
Multiple Choice:
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57) Problem #PRAFTWM "PRAFTWM - 164930 - A random sample o..." |
A random sample of 507 people participated in a worldwide study for cancer. Of the 507 people, only 142 completed the survey. Calculate the 95% confidence interval for the people who completed the survey. |
Multiple Choice:
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58) Problem #PRAFTWN "PRAFTWN - 164931 - State which of th..." |
State which of the following is TRUE. |
Multiple Choice:
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59) Problem #PRAFTWP "PRAFTWP - 164932 - Results from a na..." |
Results from a national test stated that the mean score was 65 with a standard deviation of 5. A sample of 30 students were taken to see their mean score. Results stated that they scored a mean of 58 and a standard error of 3.2 Find the 99% confidence interval. |
Algebraic Expression:
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60) Problem #PRAFT7B "PRAFT7B - 165200 - Which equation is..." |
Which equation is used in σ is not known? all x's are x-bar a. b. c. d. |
Multiple Choice:
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61) Problem #PRAFT7E "PRAFT7E - 165203 - Which equation is..." |
Which equation is used for proportions? a. b. c. d. |
Multiple Choice:
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62) Problem #PRAFT7F "PRAFT7F - 165204 - Which is not ..." |
Which is not a condition that must me met to use the following formula? |
Multiple Choice:
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63) Problem #PRAFR63 "PRAFR63 - Confidence Intervals part 1" |
Supervisors at the Ninja Quilt textile factory discovered that the thread count for their new product, The Death Blanket, has not met the standards their grandfathers had set in 1572 B.C.E, which was to be 300 count for all blankets. In reaction to this new finding they acquired 25 randomly selected products from the line and found the following information on their thread counts: 289 250 278 300 304 232 300 270 269 291 270 247 243 299 281 311 302 245 278 309 260 278 263 291 295 Suppose that the supervisors told us that they have produced 1.2 million units so far with their standard deviation being 20. Use this information to calculate the mean with a 95% confidence interval. Round your answer to the nearest tenth. |
Algebraic Expression: |
64) Problem #PRAFUEX "PRAFUEX - 165436 - What requirements..." |
What requirements have to be met to constuct a confidence interval for μ? (select all that apply) |
Multiple Choice:
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65) Problem #PRAFUEY "PRAFUEY - 165437 - There is a compan..." |
A)
There is a company named jolly rojers whole likes to make balla bergers. They like the weight of thier meat to very percise for a burger. When data on 56 burgers came back form a srs conducted teh componey said they had a 95% confidence interval. The standered deviation was .25lb and x bar was 2.5lb What is the lower critical value? |
Multiple Choice:
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B)
What is the uper critical value? round to the tenth |
Multiple Choice:
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66) Problem #PRAFUE9 "PRAFUE9 - 165446 - WHat are parts of..." |
WHat are parts of a confidence interval? |
Multiple Choice:
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67) Problem #PRAFSS9 "PRAFSS9 - 163865 - The three monkeys..." |
The three monkeys in the zoo love to eat bananas. The zoo keepers collected data on the number of bananas that was comsumed. The monkeys are shown to eat an average of 15 bananas each day with a standard deviation of 2. What is the 99% confidence interval for the mean number of bananas? round answer to nearest whole number |
Multiple Choice:
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Hints: |
x bar±z(σ/√n) |
answer is (12,18) |
68) Problem #PRAFSQT "PRAFSQT - 163789 - Leah was absent o..." |
Leah was absent on the day her class took a test. The following is the score for her class.
Construct a 90% confidence interval for the mean score μ? |
Multiple Choice:
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Hints: |
x-bar is 85.88 |
x-bar±z(σ/√n) 85.88±1.645(10/√16) |
81.77, 89.99 |
69) Problem #PRAFSUW "PRAFSUW - 163916 - A basketball manu..." |
A basketball manufacturing company wants to be accurate within ±.5 inches with a 95% confidence and standard deviation of 2. How large a sample of basketballs should be measured? round to nearest whole number |
Algebraic Expression:
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Hints: |
1.96(2/√n) ≤ .5 |
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70) Problem #PRAFSWB "PRAFSWB - 163960 - Antony is the cre..." |
A)
Antony is the creator of a multi-million dollar company selling houses. To ensure that he and his company are doing a good job, he does a survey on 50 random people each year to see how happy they are with their new home.This past year, the average number of people happy with their home was 43 with a standard deviation of 3. What is the margin of error with a confidence level of 99%? Round two decimal places. *write it in the format of: (-, +)!!! |
Algebraic Expression:
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Hints: |
Use the formula: x-bar±(z*)(σ/√n) |
B)
What is the lower limit? Round wo decimal places. |
Algebraic Expression:
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Hints: |
use the equation: estimate±(z*)(σ) |
C)
What is the upper limit? Round two decimal places. |
Algebraic Expression:
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Hints: |
estimate±(z*)(σ) |
71) Problem #PRAFS4W "PRAFS4W - 164164 - a crack team of s..." |
A)
a crack team of scientests try to see how long people can hold their breathe for underwater. there are 12 subjects in a chamber filled with 105 liters of water. the times in seconds are below. 91.9, 97.8, 111.4, 122.3, 105.4, 95.0, 103.8, 99.6, 96.6, 119.3, 104.8, 101.7 what is the mean time? round to the nearest tenth |
Algebraic Expression:
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B)
a crack team of scientests try to see how long people can hold their breathe for underwater. there are 12 subjects in a chamber filled with 105 liters of water. the times in seconds are below. 91.9, 97.8, 111.4, 122.3, 105.4, 95.0, 103.8, 99.6, 96.6, 119.3, 104.8, 101.7 what is t and p? round to the nearest ten thousandth |
Multiple Choice:
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C)
a crack team of scientests try to see how long people can hold their breathe for underwater. there are 12 subjects in a chamber filled with 105 liters of water. the times in seconds are below. 91.9, 97.8, 111.4, 122.3, 105.4, 95.0, 103.8, 99.6, 96.6, 119.3, 104.8, 101.7 Do you reject the null? |
Multiple Choice:
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72) Problem #PRAFS4B "PRAFS4B - 164146 - The NFL combine m..." |
The NFL combine measures many attributes of an athlete, a certain portion of the test ranks certain positions specific skills. The scores that can be achieved for a skills test ranges from a 1.00 to a 5.00. the scores of 17 quaterbacks had a symmetric distribution with x-bar=1.67 and s=0.25. give a 95% confidence interval for the mean score of the quarterbacks. |
Multiple Choice:
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73) Problem #PRAFSTD "PRAFSTD - 163869 - a car company is ..." |
a car company is charging a fee for those who buy cars on credit and charge over 2400 to a card. they are only charging 200 recent customers this fee. they then compare the amount of charges the customers had last year and the current year. the mean increase is $332 and the standard deviation is $108. give a 99% confidence interval for the mean of the increase. |
Multiple Choice:
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74) Problem #PRAFS4C "PRAFS4C - Conf. Int. #1 " |
There is a population of heights of preschoolers, a sample of 11 children are used to estimate the population mean and standard deviation. If there is a 95% confidence interval for the mean, then the confidence interval contains values that are within how many standard deviations of the mean? Round your answer to the nearest hundreth. |
Algebraic Expression:
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75) Problem #PRAFS4H "PRAFS4H - Conf. Int. #2" |
Given a sample of 25 hourly wages from a population with a sample mean of 38, and a standard deviation of 6.5, what is the 95% confidence interval of the mean? |
Multiple Choice:
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76) Problem #PRAFS4N "PRAFS4N - Conf. Int. #3+4" |
A)
Given a sample (N=9) of the workhour of adults, with a mean of 49 and a standard deviation of 4, and a 99% confidence interval of the mean, what is the lower limit? Round your answer to the nearest hundreth. |
Algebraic Expression:
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B)
Find the upper limit using the same data. Round your answer to the nearest hundreth. |
Algebraic Expression:
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77) Problem #PRAFS4R "PRAFS4R - Conf. Int. #5" |
A higher confidence interval will give a _________ confidence interval. |
Multiple Choice:
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78) Problem #PRAFS6B "PRAFS6B - 164208 - For a science fai..." |
For a science fair project, a student is finding the boiling temps of 6 different liquids. He finds the mean of the boiling temps to be 101.82 degrees. He knows the standard deviation of the procedure is 1.2 degrees. What is the confidence interval with a confidence level of 90%? write answer as ( , ) round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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Hints: |
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Hints: |
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79) Problem #PRAFSRV "PRAFSRV - Problem #163822" |
A man is taken into custody and will go on trial for a series of armed robberies. A local news station creates an online poll of whether or not their listeners think the man is guilty. 160 people answer the poll, with 105 saying he is guilty and 55 saying he is not. What is the confidence interval with a confidence level of 95%? write answer as ( , ), with the lower number first. |
Exact Match (case sensitive):
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Hints: |
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Hints: |
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Hints: |
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Hints: |
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80) Problem #PRAFS6F "PRAFS6F - 164212 - A quality control..." |
A)
A quality control official at a candy packaging facility wants to make sure that there is a mean amount of 22 candies per package. Of the 16 packages he checked, he found a sample mean of 18 with a standard deviation of 1. Is this data good enough evidence to prove that the facility is under-packaging the candy? Fill in the blank. X~N( , ). Type only ( , ). |
Algebraic Expression:
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B)
Refer to the previous problem. What is Z? |
Algebraic Expression:
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C)
Refer to the previous problem. What is the p value? |
Algebraic Expression:
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D)
If the alpha is .05, what should the conclusion be, reject or fail to reject? |
Multiple Choice:
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81) Problem #PRAFS6H "PRAFS6H - 164214 - To sew a certain ..." |
A)
To sew a certain fabric, needles with a diameter of 2mm are needed, so a seamstress buys a package of 50 needles claiming to have diameters of 2mm. If the needles are too large the fabric will tear, but if they are too small, the seamstress cannot thread the needle. The seamstress examines half of the 50 needles and finds that they have a sample mean diameter of 2.02 and a standard deviation of .07. Will the needles work? First, fill in the blank. x bar~N( , ). type only ( , ). |
Algebraic Expression:
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B)
Refer to the previous problem. What is Z? round to the nearest hundredth. |
Algebraic Expression:
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C)
Refer to the previous problem. What is the p value? |
Algebraic Expression:
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Hints: |
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D)
Refer to the previous problem. Do we reject or fail to reject the null? |
Multiple Choice:
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82) Problem #PRAFSXB "PRAFSXB - 163991 - Tests on the weig..." |
A)
Tests on the weight of three kinds of bird feathers result in 0.8403, 0.8368, and 0.8447 grams. The standard deviation of this distribution is 0.0068 grams. What is the 99% confidence interval for the mean weight of all three feathers? First, find z*. |
Algebraic Expression:
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B)
Next, what is the margin of error? |
Algebraic Expression:
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C)
Now, find the 99% confidence interval. |
Multiple Choice:
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83) Problem #PRAFSRH "PRAFSRH - 163811 - According to medi..." |
A)
According to medical specialists, the average height of eighteen-year-old women is 1.64 meters, with a standard deviation of .27 meters. You are looking at 64 randomly chosen women. You are trying to find a 95% confidence interval. What is the margin of error? Round to three decimals. |
Algebraic Expression:
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Hints: |
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B)
What is the lower limit of the 95% confidence interval? Round to three places. |
Algebraic Expression:
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Hints: |
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C)
What is the upper limit of the 95% interval? Round to three decimal places. |
Algebraic Expression:
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Hints: |
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84) Problem #PRAFSTG "PRAFSTG - 163872 - A survey shows th..." |
A)
A survey shows that more than at the average restaurant, 30 people dine and dash every month, with a standard deviation of 7. In one month, an average of 35 people dine and dash from 15 Boston-area restaurants. What is the z-score for this data? |
Algebraic Expression:
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Hints: |
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B)
What is the p-value? |
Algebraic Expression:
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Hints: |
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C)
Given α = 0.05, can we reject the null or do we fail to reject the null? |
Multiple Choice:
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85) Problem #PRAFS3G "PRAFS3G - 164120 - A firm is conduct..." |
A firm is conducting a survey on peoples' yearly salary. They surveyed 500 people and determined the average wage to be $50,000. Suppose that the standard deviation is $2000. Determine the 99% confidence interval for the mean pay of the population. |
Multiple Choice:
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Hints: |
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86) Problem #PRAFS55 "PRAFS55 - 164202 - A marketing agenc..." |
A marketing agency is polling the public about service satisfaction. 657 people answered the poll, with 65% of the people saying that they are satisfied with the company's services. Find the 95% confidence interval for the population of people who said that they were satisfied. |
Multiple Choice:
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Hints: |
(p-hat) + or - (Z*)(√((p-hat)(1-(p-hat)))/sample size) |
(.65) + or - (1.960)(√((.65)(.35))/(657)) Now solve and determine the lower and upper bound. |
87) Problem #PRAFS6A "PRAFS6A - 164207 - Bob wants to esti..." |
Bob wants to estimate the proportion of the students in his school who ate school lunch. He polled 56 students and 36 of them said that they ate school lunch. Find the 99.5% confidence interval for the students who ate school lunch. |
Multiple Choice:
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Hints: |
(p-hat) + or - (Z*)(√((P-hat)(1-(p-hat)))/(sample size)) |
(.64) + or - (2.807)(√((.64)(.36))/(56)) |
88) Problem #PRAFS6E "PRAFS6E - 164211 - A group of 25 man..." |
A group of 25 managers are gathered to decide the wage to pay their employees. They came to an agreement that the average wage hould be $25/hr, with a standard deviation of $5. Find the 99% confidence interval for the mean wage. |
Multiple Choice:
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Hints: |
(x-bar) + or - (t)(standard deviation/√sample size) The value of t can be found of the t-table and is equal to one less than the sample size. In this case, our sample size is 25 so we will be looking at 24. Matching 99% to 24 and we get a t value of 2.797. |
(25) + or - (2.797)(5/√25) |
89) Problem #PRAFSS5 "PRAFSS5 - 163861 - Shawna is conduct..." |
Shawna is conducting a survey for her senior class regarding how many persons have tried lobster. 211 of her 383 classmates responded that they had indeed tried lobster. Calculate the confidence interval, both lower and upper bounds, for those who responded they had tried lobster given 95% confidence. Round to the nearest tenth. |
Algebraic Expression:
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90) Problem #PRAFS5P "PRAFS5P - 164188 - Lewis is conducti..." |
Lewis is conducting an inventory on the flavors of ice cream he has to sell in his store. Of the 50 packages of ice cream, 17 are vanilla. Calculate a confidence interval, both lower and upper bounds, for vanilla ice cream given 95% confidence. Round to the nearest hundredth. |
Algebraic Expression:
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91) Problem #PRAFS5X "PRAFS5X - 164196 - Vanessa is compil..." |
Vanessa is compiling data on a survey she conducted. Of the 46 people she asked, 19 of them replied positively. Find the confidence interval for those who responded positively, given 95 confidence. Round to the nearest hundredth. |
Algebraic Expression:
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92) Problem #PRAFSSU "PRAFSSU - 163852 - A university want..." |
A university wants to know more about the knowledge of students regarding international events. The are concerned that their students are uninformed in regards to new from other countries. A standardized test is used to assess students knowledge of world events (national reported mean=65, S=5). A sample of 30 students are tested (sample mean=58) Compute a 99 percent confidence interval based on this sample's data. How do these students compare to the national sample? What is the standard error? |
Algebraic Expression:
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93) Problem #PRAFSSW "PRAFSSW - 163854 - A university want..." |
A university wants to know more about the knowledge of students regarding international events. The are concerned that their students are uninformed in regards to new from other countries. A standardized test is used to assess students knowledge of world events (national reported mean=65, S=5). A sample of 30 students are tested (sample mean=58, Standard Error=3.2). Compute a 99 percent confidence interval based on this sample's data. How do these students compare to the national sample? What is the confidence interval? |
Algebraic Expression:
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94) Problem #PRAFSSX "PRAFSSX - 163855 - A sample of stude..." |
A sample of students from an introductory psychology class were polled regarding the number of hours they spent studying for the last exam. All students anonymously submitted the number of hours on a 3 by 5 card. There were 24 individuals in the one section of the course polled. The data was used to make inferences regarding the other students taking the course. There data are below:
|
Algebraic Expression:
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95) Problem #PRAFSSZ "PRAFSSZ - 163857 - A sample of stude..." |
A sample of students from an introductory psychology class were polled regarding the number of hours they spent studying for the last exam. All students anonymously submitted the number of hours on a 3 by 5 card. There were 24 individuals in the one section of the course polled. The data was used to make inferences regarding the other students taking the course. There data are below:
|
Algebraic Expression:
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96) Problem #PRAFSSQ "PRAFSSQ - 163848 - A sample of Alzhe..." |
A sample of Alzheimer's patients are tested to assess the amount of time in stage IV sleep. It has been hypothesized that individuals sufferering from Alzheimer's Disease may spend less time per night in the deeper stages of sleep. Number of minutes spent is Stage IV sleep is recorded for sixty-one patients. The sample produced a mean of 48 minutes (S=14 minutes) of stage IV sleep over a 24 hour period of time. Compute a 95 percent confidence interval for this data. What does this information tell you about a particular individual's (an Alzheimer's patient) stage IV sleep? What is the standard error of mean? |
Algebraic Expression:
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97) Problem #PRAFSSR "PRAFSSR - 163849 - A sample of Alzhe..." |
A sample of Alzheimer's patients are tested to assess the amount of time in stage IV sleep. It has been hypothesized that individuals sufferering from Alzheimer's Disease may spend less time per night in the deeper stages of sleep. Number of minutes spent is Stage IV sleep is recorded for sixty-one patients. The sample produced a mean of 48 minutes (S=14 minutes) of stage IV sleep over a 24 hour period of time. Compute a 95 percent confidence interval for this data. What does this information tell you about a particular individual's (an Alzheimer's patient) stage IV sleep? What percent is the confidence interval at? |
Algebraic Expression:
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98) Problem #PRAFSRP "PRAFSRP - 163816 - A sample of Alzh..." |
A sample of Alzheimer's patients are tested to assess the amount of time in stage IV sleep. It has been hypothesized that individuals sufferering from Alzheimer's Disease may spend less time per night in the deeper stages of sleep. Number of minutes spent is Stage IV sleep is recorded for sixty-one patients. The sample produced a mean of 48 minutes (S=14 minutes) of stage IV sleep over a 24 hour period of time. Compute a 95 percent confidence interval for this data. What does this information tell you about a particular individual's (an Alzheimer's patient) stage IV sleep? What does T equal? |
Algebraic Expression:
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99) Problem #PRAFHJH "PRAFHJH - 155937 - Your Statistics t..." |
Your Statistics teacher poses you this question" Calulate the mean number of clubs each senior participates in". In that questions, what is the parameter? |
Multiple Choice:
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100) Problem #PRAFHJJ "PRAFHJJ - 155938 - 16% of jelly bean..." |
A)
16% of jelly beans are red if randomly 200 are selected. The standard deviation is .051. Find the new standard deviation. Round to the nearest hundreth. |
Algebraic Expression:
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Hints: |
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B)
16% of jelly beans are red if randomly 200 are selected. The standard deviation is .051. Find the new standard deviation. Round to the nearest hundreth. |
Algebraic Expression:
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Hints: |
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C)
What is th probability that greater than 13% of the jelly beans chosen are red? Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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101) Problem #PRAFHJK "PRAFHJK - 155939 - According to the ..." |
According to the Central Limit Theorum when does data approach normality? |
Multiple Choice:
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102) Problem #PRAFSZK "PRAFSZK - Khaleel Asks.." |
A)
Khaleel asks Mr. Simoneau what the 99% confidence interval is for the amount of yards thrown by a SRS of 20 quarterbacks in past superbowl games. X-bar= 306.3, standard deviaton= 43 |
Algebraic Expression:
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B)
Taking the same data from the previous question Khaleel now wants to know what the 90% confidence interval is. X-bar still equals 306.3 and standard deviation= 43 |
Algebraic Expression:
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103) Problem #PRAFSSV "PRAFSSV - Celtics" |
A)
A sample of 1785 adults were asked over the course of seven days if they were opposed to the Nate Robinson and Kendrick Perkins trade for Jeff Green. 750 responded "yes." Calculate the 99% interval for the proportion of adults who were opposed of the Celtics trade for Jeff Green |
Algebraic Expression:
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B)
How large a sample would be required to obtain a margin of error of 0.01 in a 99% confidence interval for the proportion of people who opposed the Celtic trade for Jeff Green? Use p=0.5 |
Multiple Choice:
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104) Problem #PRAFSRK "PRAFSRK - 163813 - A sportscaster fi..." |
A sportscaster finds that xbar is 114.9 and s= 9.3 for the average yards per game by 27 running backs in past years super bowls. What is the standard error of the mean? |
Algebraic Expression:
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105) Problem #PRAFSS7 "PRAFSS7 - 163863 - There is a sample..." |
There is a sample of 45 people and 78% of them prefer cheerios to kix with a standard deviation of 11 nationally 76% of people prefer cheerios to kix find a 90% confidence interval for this data and round to the nearest hundredth |
Multiple Choice:
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106) Problem #PRAFSRT "PRAFSRT - 163820 - x-bar= 35 n=8 sta..." |
x-bar= 35 n=8 standard deviation= 1.7 find a 95% confidence interval for this data set. |
Multiple Choice:
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107) Problem #PRAFSRG "PRAFSRG - 163810 - xbar=3 mean=4.5 s..." |
xbar=3 mean=4.5 standard deviation=.345 n=77 confidence interval=80% round to the nearest hundredth |
Multiple Choice:
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108) Problem #PRAFR64 "PRAFR64 - 163271 - The national aver..." |
The national average of an AP Calc test is a 65 There is a group of 25 students that were tested and the mean score was 66.7 with a standard deviation of 2 What is Hnull, Halternative, Z, and the p-value? |
Ungraded Open Response: |
109) Problem #PRAFSQF "PRAFSQF - 163778 - The height of chi..." |
The height of children at an elementary school follows a normal distribution with an x-bar of 5.5 feet and a standard deviation of 0.12. You need to find the probability that the mean of a random sample of 100 students will be taller than 5.9 feet. Using a 99% confidence interval, what is the lower limit? Round to the nearest hundredth. |
Algebraic Expression:
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110) Problem #PRAFS5T "PRAFS5T - 164192 - A study of restau..." |
A study of restaurant chain cleanliness sent questionnaires to an SRS of 160 fast food chains. There were 114 feedback. The average sanitation rating that these 114 fast food restaurants got in an inspection was a 11.8 (out of 15) with a standard deviation of 3.2. Give a 99% confidence interval for the mean cleanliness rating that these restaurants received. |
Multiple Choice:
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111) Problem #PRAFS5F "PRAFS5F - 164181 - A random survey i..." |
A random survey interviewed 468 people randomly selected in the U.S., asking what they bake at home. The survey found that 56% of the people they interviewed said that they bake cookies. Using a 95% confidence level, what is the upper limit? Round to the nearest hundredth. |
Algebraic Expression:
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112) Problem #PRAFTT5 "PRAFTT5 - 164853 - What is the small..." |
A)
What is the smallest sample size required to a provide a 95% onfidence interval for a mean, if it is important that the interval be no longer than 1cm? You may assume that the population is normal with a variance of 9 cm2 |
Algebraic Expression:
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B)
Which of the following is true? I. When the margin of error is small the confidence is high II. When the margin of error is small the confidence is low. III. A confidence interval is a type of point estimate IV. A population mean is an example of point estimate. |
Multiple Choice:
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C)
900 high school freshmen were randomly selected for the national survey. Among them the average gpa was 2.7, and the nat standard deviation is 0.4 what is the margin of error, assuming a 95% confidence level? |
Algebraic Expression:
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D)
A national achievement is given to 4th graders bThe test has a mean score of 100 and a standard deviation of 15. If jane z-score is 1.2, what was her score on the test? |
Algebraic Expression:
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E)
Is it possible for the 95% interval to contain the population while the 99% confidence interval does not? |
Multiple Choice:
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113) Problem #PRAFS6M "PRAFS6M - 164217 - A sample of Cance..." |
A sample of Cancer patients are tested to see how long they experience deep sleep. A sample of 61 patients are taken with a mean of 48 minutes and a SD of 14 minutes. Compute a 95% confidence interval. Answer High intervalr,Low interval. Ex: 100,1 round to tenths place |
Algebraic Expression:
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Hints: |
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114) Problem #PRAFS58 "PRAFS58 - 164205 - A universtity wan..." |
A universtity wants to know regarding international events. They are concerned that their students are uninformed in regards to news from other countries. A standardized test is used to assess students knowledge of world events (National Mean=65, Standard deviation=5). A sample of 30 students scored an average of 58 with a SD of 3.2. What is the 99% confidence inverval based on the data . Give high number first, low number. EX: 100,1 round to hundredths place no space |
Algebraic Expression:
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Hints: |
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115) Problem #PRAFS5Z "PRAFS5Z - 164198 - The recommended p..." |
The recommended price for a jacket is 150$. A random sample taken of 16 stores showed an average price of 141$ for the jacket with a standard deviation of 4$. What is the interval for 95% confidence. Round to the hundreths place. |
Algebraic Expression:
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Hints: |
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116) Problem #PRAFS5B "PRAFS5B - 164177 - A toy designer wa..." |
A toy designer wants to find out how long it takes to assemble a toy. A sample of 16 times yielded an average time of 19.92 minutes with a standard deviation of 5.73 minutes. Assuming a normal bell curve give a 95% confidence interval for the mean assembly time. Give answer high number,low number no spaces. Ex:100,1 |
Algebraic Expression:
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Hints: |
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117) Problem #PRAFS5C "PRAFS5C - 164178 - A simple random s..." |
A)
A simple random sample of 43 pairs of shoes in a shoe store is collected. The sample has a mean shoe size of 7. Assume the distribution is non-normal, and the sigma = size 5. We will calculate the 95% confidence interval of the mean shoe sizes for all the pairs of shoes in the store later on. What is the number that represents the point estimate for this problem? |
Algebraic Expression:
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Hints: |
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B)
Calculate the margin of error for this problem. Round to the nearest hundredths. Hint: m = z* x (sigma/square root of n) |
Algebraic Expression:
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Hints: |
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C)
What is the Lower Limit? Lower Limit = Point Estimate - Margin of Error |
Algebraic Expression:
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Hints: |
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D)
What is the Upper Limit? Hint: Upper Limit = Point Estimate + Margin of Error |
Algebraic Expression:
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Hints: |
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E)
What is the 95% confidence interval of the mean shoe sizes for all pairs of shoes in the store? |
Multiple Choice:
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Hints: |
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118) Problem #PRAFSUE "PRAFSUE - 163901 - A sample of 15 pe..." |
A)
A sample of 15 people report how many hours of television they watch in a week. The data is below. Amount in Hours 15 17 11 24 16 13 13 26 22 19 11 18 20 21 16 What is the sample mean? Round to the nearest tenth. |
Algebraic Expression:
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Hints: |
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B)
What is the sample standard deviation? Round to the nearest tenth. |
Algebraic Expression:
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Hints: |
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C)
Now find the population standard deviation given the information you have already calculated. Round to the nearest tenth. |
Algebraic Expression:
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Hints: |
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D)
We want to find the 95% confidence interval. Our next step is to find Z*. Round to the nearest thousandth. |
Algebraic Expression:
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Hints: |
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E)
Now find the confidence interval. Use all of the data that you have collected. Submit in the form of __, __ Round to the nearest tenth. |
Algebraic Expression:
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Hints: |
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119) Problem #PRAFSUA "PRAFSUA - 163897 - What does a conf..." |
What does a confidence interval measure? Check all that apply. |
Check All That Apply:
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120) Problem #PRAFSUD "PRAFSUD - 163900 - The following are..." |
A)
The following are the sample amount of fluid ounces in a water bottle of a particular brand. 16.9 17.0 16.5 16.3 17.0 16.9 16.8 16.7 16.9 17.1 The standard deviation of the population is 2.3 ounces. The distribution is approximately normal. What is the 95% confidence interval of for the population p? |
Multiple Choice:
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Hints: |
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B)
In this setting, what does "95% confident" means? |
Multiple Choice:
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C)
Calculate the 99% confidence interval. |
Multiple Choice:
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121) Problem #PRAFST7 "PRAFST7 - 163894 - A poll is taken t..." |
A poll is taken to find out how many people prefer apples over oranges. It takes data from 1764 people. Of these, 12% prefer apples. Explain to someone why we can't just say that 12% of the population likes apples. |
Ungraded Open Response: |
122) Problem #PRAFTQQ "PRAFTQQ - 164747 - As the confidence..." |
As the confidence interval decreases, the margin of error |
Multiple Choice:
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123) Problem #PRAFTRB "PRAFTRB - 164766 - As margin of erro..." |
As margin of error decreases, the σ |
Multiple Choice:
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124) Problem #PRAFS7P "PRAFS7P - 164250 - A 95% confidnce i..." |
A 95% confidnce interval for the SAT scores of high school juniors is 1600 to 2000. This means which of the following: |
Multiple Choice:
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125) Problem #PRAFTQN "PRAFTQN - 164745 - The 68-95-99.7 ru..." |
The 68-95-99.7 rule tells us that in 95% of all samples the mean score (x-bar) for the sample will be within how many standard deviations of the population mean score μ? |
Multiple Choice:
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126) Problem #PRAFST4 "PRAFST4 - 163891 - Find the 90% conf..." |
Find the 90% confidence for this data set: 10 15 28 5 2 40 30 29 50 8 7 18 |
Multiple Choice:
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Hints: |
90% Confidence= 1.645 20.167±1.645(16÷√12)= (12.569, 27.765) |
127) Problem #PRAFSUF "PRAFSUF - 163902 - Find the m..." |
Find the margin of error for 95% confidence in a situation where the standard deviation is 53 and the sample size is 90. |
Multiple Choice:
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Hints: |
1.960(53÷√90)= 10.95 |
128) Problem #PRAFSUH "PRAFSUH - 163904 - In a class of 32 ..." |
In a class of 32 students, 8 of them thought they had failed a math test. Find the 95% confidence interval for the true proportion of students that feel they failed the test. |
Multiple Choice:
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Hints: |
95% Confidence= 1.960 0.25±1.960*√[(0.25)(0.75)÷(32)] *Confidence Intervals for Proportion Formula |
129) Problem #PRAFTQC "PRAFTQC - 164736 - Adrian knows the ..." |
Adrian knows the mean melon size on his farm for the whole population of melons from extensive work and wants to have a 90% confidence interval for the mean size of his melons that he could expect next year given all the same conditions. The value of the mean of the population is 7.8kg and the sigma for the population is 1.7kg and the size of the sample will be 900. What is this 90% confidence interval? Note: Answer in this Format: (12.3, 45.6) 4 Decimal Places |
Algebraic Expression:
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Hints: |
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130) Problem #PRAFTRY "PRAFTRY - 164786 - If Makoto is inte..." |
If Makoto is interested in the average length of butcher knives produced by a certain industry from which he has attained a set of statistics for a sample distribution of 577 butcher knives with a mean length of 21cm and a standard deviation of 5.6cm, what is a 98% confidence interval for this distribution? Note: Answer in this Format: (12.3, 45.6) 4 Decimal Places |
Algebraic Expression:
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Hints: |
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131) Problem #PRAFTSE "PRAFTSE - 164800 - If Lelouch is cur..." |
If Lelouch is curious about the fail rate of shield algorithms systems in new gen defense systems and has had tests done on 29 defense systems and has found that the mean fail rate of the systems is 13.42% with a standard deviation of 6.78% for the sample distribution. If Lelouch desires a 99.9% confidence interval, what is the confidence interval for this distribution? Note: Answer in this Format: (12.3, 45.6) 4 Decimal Places |
Algebraic Expression:
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Hints: |
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132) Problem #PRAFSXD "PRAFSXD - 163993 - Confidence 3-4" |
A)
A random sample of 100 adults in Boston showed that 65% had taken a higher level of math than Algebra. What is a 95% confidence interval of those that have taken a hight level of math? Round to the nearest hundredth. |
Multiple Choice:
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B)
Provide a 90% confidence interval. Round to the nearest thousandth. |
Multiple Choice:
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133) Problem #PRAFSXE "PRAFSXE - Confidence 5" |
The head of the MBTA wants to make sure its buses are running on time. A sample size of 18 of the 39 buses was taken, revealing that it takes an average time was 30.25 minutes to get from Forest Hills to Back Bay Station, with a standard deviation of 5.4 minutes. Find a 95% confidence interval for the mean travel time. Round to the nearest tenth. |
Multiple Choice:
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134) Problem #PRAFSZR "PRAFSZR - 164066 - As the confidence..." |
As the confidence level increases, the margin of error _______ . |
Multiple Choice:
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135) Problem #PRAFSZS "PRAFSZS - 164067 - The GPA's of a sa..." |
The GPA's of a sample of 25 high school students in California range from 1.0 to 5.0 with an x-bar of 2.94 and a standard deviation of 0.25. Give a 95% confidence interval for the mean GPA's of California students. |
Multiple Choice:
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136) Problem #PRAFSZ6 "PRAFSZ6 - 164079 - If σ i..." |
If σ is known, which equation is used to find the confidence interval? a) x-bar ± z*(σ/√n) b) x-bar ± z*(s/√n) |
Multiple Choice:
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137) Problem #PRAFSZ9 "PRAFSZ9 - 164082 - What is x-bar cal..." |
What is x-bar called when constructing a confidence interval? |
Multiple Choice:
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138) Problem #PRAFSUP "PRAFSUP - 163909 - Your statistics c..." |
Your statistics class wants to know how satisfied teachers at your school are with the electronic equipment in their classroom. A survey is given to all 310 teachers in the school. The teachers respond using a seven-point scale, with a score of 1 being "not satisfied," a score of 4 being "moderately satisfied," and a score of 7 being "very satisfied." The mean response was 5.4 and the standard deviation was 0.9. Give a 95% confidence interval for the mean of the entire population of teachers in the country. Round your answer to the nearest hundredth. |
Multiple Choice:
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Hints: |
x-bar = point estimate +/- t* (s/sqrt.n)
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139) Problem #PRAFS26 "PRAFS26 - 164110 - Your statistics t..." |
Your statistics teacher wants to know how well his students did on the last test, but he has only graded 14 random tests. The average score was 87.5% with a standard deviation of 0.8.Give a 95% confidence interval for the mean of all of his students. Round your answer to the nearest hundredth. |
Multiple Choice:
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Hints: |
x-bar = point estimate +/- t* (s/sqrt.n)
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140) Problem #PRAFS3H "PRAFS3H - 164121 - A student in your..." |
A student in your statistics class wants to know how many hours on average high school students spend on Facebook each night. To determine this, the student obtains a simple random sample of 78 students in your school. The average is 3.2 hours and the standard deviation is 0.4 hours. Give the 90% confidence interval for the average number of hours students in your school spend on Facebook each night. Round your answer to the nearest hundredth. |
Multiple Choice:
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141) Problem #PRAFS6Q "PRAFS6Q - 164220 - Find the point es..." |
Find the point estimate of the given information... Z* = 1.036 Sigma = .5 n = 50 |
Algebraic Expression:
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142) Problem #PRAFS6R "PRAFS6R - 164221 - In finding the po..." |
In finding the point estimate what number is used in a confidence interval of 95%? Round to the nearest hundredth. |
Algebraic Expression:
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143) Problem #PRAFS6S "PRAFS6S - 164222 - What are the guid..." |
What are the guidelines for confidence intervals for a population mean when sigma is known? |
Check All That Apply:
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144) Problem #PRAFTUX "PRAFTUX - 164878 - Explain how to go..." |
Explain how to go about finding a p-value. |
Ungraded Open Response: |
145) Problem #PRAFTT9 "PRAFTT9 - 164857 - The equation for ..." |
The equation for marginal error is z*(theta/square root of n). Find the 95 % confidence interval for data with a standard deviation of 10 and a sample size of 50. |
Algebraic Expression:
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146) Problem #PRAFTT6 "PRAFTT6 - 164854 - When testing a st..." |
When testing a statement which hypothesis are you testing? The null hypothesis or the alternative? |
Algebraic Expression:
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147) Problem #PRAFST9 "PRAFST9 - 163896 - As the sampl..." |
As the sample size increases, the confidence interval... |
Multiple Choice:
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148) Problem #PRAFSUJ "PRAFSUJ - 163905 - An SRS of the tes..." |
An SRS of the test scores on a Statistics test of 10 students has a mean of 87. The standard deviation of the sample is 12. What is the point estimate in this problem? |
Algebraic Expression:
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Hints: |
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149) Problem #PRAFSUN "PRAFSUN - 163908 - If you have a sam..." |
If you have a sample size of 36 and are looking for the 90% confidence interval with the standard deviation unknown, what number do you use for your t*? Look at the t-table and type the number as it appears on the table. |
Algebraic Expression:
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Hints: |
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150) Problem #PRAFST5 "PRAFST5 - 163892 - A retailer..." |
A retailer is trying to look for sites for a convenience store in a town and wants to know the proportion of ratepayers who are in favor of this. If the estimate is required to be within 0.1 of the true proportion, would a random sample of size n = 100 from the council records be enough for a 95% confidence interval of this precision? |
Multiple Choice:
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151) Problem #PRAFS6W "PRAFS6W - 164226 - A random sample o..." |
A random sample of 150 men found that 88 of the men exercise regurlarly, whilea random sample of 200 women found that 130 of the women exercise regurlarly. Based on the results, construct and interpret a 95% confidence interval for the difference in the proportions of women and men who exercise regurlarly. |
Algebraic Expression:
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152) Problem #PRAFS6X "PRAFS6X - 164227 - A can of juice co..." |
A can of juice contains a mean of 13 ounces with a standard deviation of 0.5 ounce. The distribution of the juice cans is approximately Normal. What is the probability that a case of 12 cereal boxes contains a total of more than 160 ounces? |
Algebraic Expression:
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153) Problem #PRAFTUZ "PRAFTUZ - 164880 - Biologists studyi..." |
Biologists studying the healing of skin wounds measured the rate at which new cells closed a razor cut made in the skin of an anesthetized newt. Here are data from 18 newts, measured in micrometers per hour: 29, 27, 34, 40, 22, 28, 14, 35, 26, 35, 12, 30, 23, 18, 11, 22, 23, 23. How large a sample would enable you to estimate the mean healing rate of skin wounds in newts within a margin of error of 1 mircrometer per hour with 90% confidence? (Round to the nearest whole number) |
Algebraic Expression:
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154) Problem #PRAFUET "PRAFUET - 165432 - A manufacturer if..." |
A manufacturer if pharmaceutical products analyzes a specimen from each batch of a product to verify the concentration of the active ingredient. The chemical analysis is not perfectly precise. Repeated measurements on the same specimen give slightly different results. The results of repeated measuremnets follow a normal distribution quite closely. The analysis procedure has no bias, so the mean μ of the population of all measurements is the true concentration in the specimen. The standard deviation of this distribution is known to be σ=0.0068 grams per liter. The laboratory analyzes each specimen three times and reports the mean results. Three analyses of one specimen five concentrations 0.8403, 0.8363, 0.8447. Find the margin of error for 90% confidence if the manufacturer measures the tension of 80 video monitors. |
Multiple Choice:
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155) Problem #PRAFUEU "PRAFUEU - 165433 - A study of the ca..." |
A study of the career paths of hotel general managers sent questionnaires to an SRS of 160 hotels belonging to major US hotel chains. There were 114 responses. The average times these 114 genereal managers had spent with their current company was 11.78 years. How large a sample of the hotel managers would be needed to estimate the mean μ within ±1 year wutg 99% confidence? (Round to the nearest whole number) |
Algebraic Expression:
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156) Problem #PRAFTT7 "PRAFTT7 - 164855 - A confidence inte..." |
A confidence interval is used to determine the reliability of an estimate; how confident we are that the estimate is accurate. For exmaple, a group of students take the SAT I Reasoning Test, and a teacher declares that the mean score of the students will about 1800. If we say that the teacher estimated the score within a 95% confidence interval, we mean that 95% of the scores will fall within 1800 (plus or minus the standard deviation, which we will not deal with... yet). Do you understand this concept so far? |
Multiple Choice:
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157) Problem #PRAFTT8 "PRAFTT8 - 164856 - The 68-95-99.7 ru..." |
The 68-95-99.7 rule says that in 95% of all samples, the mean score x-bar for the sample will be within two standard deviations of the population mean score mu. Let's now go back to the previous exmaple. A mean SAT score of 1800, and a standard deviation of 100. Given these information, we can conclude that 95% of the test takers will be between 1600 to _____? |
Exact Match (case sensitive):
|
158) Problem #PRAFUEB "PRAFUEB - 165417 - A survey was give..." |
A survey was given to 400 lawyers in New York City. The survey indicates that the average time each lawyer has worked at his/her current firm was 12 years, with a standard deviation of 3.2 years. Construct a 95% confidence interval for the mean number of years each lawyer has worked at his/her current firm. Give answer in the form: ###, ### (Include the comma) Round your answer to the nearest hundredth decimal. |
Algebraic Expression:
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159) Problem #PRAFUED "PRAFUED - 165419 - Little Johnny is ..." |
Little Johnny is cutting squares for his art project. The five squares he have the follow area: 9.02, 9.543, 9.674, 9.1, 9.222. Find the 90% confidence interval of these measurements. Assume that the standard deviation to be 0.30 Round your answer to the nearest hundredth. |
Algebraic Expression:
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160) Problem #PRAFTAY "PRAFTAY - 164352 - True or False? A ..." |
True or False? A confidence interval uses sample data to estimate an unknown population parameter with an indication of how accurate the estimate is and of how confident we are that the result is correct. |
Algebraic Expression:
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161) Problem #PRAFTAZ "PRAFTAZ - 164353 - In a poll, 30 per..." |
In a poll, 30 percent of 3000 adults said that they did not like their job. This poll interviewed 1800 men and 1,200 women. The margin of error for men was +/-2 percentage points, and women was +/-4. Why is there a greater margin of error for women? |
Multiple Choice:
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162) Problem #PRAFTAT "PRAFTAT - 164347 - When the standard..." |
When the standard deviation of a statistic is estimated from the data, the result is called the... |
Multiple Choice:
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163) Problem #PRAFSZJ "PRAFSZJ - 164060 - In a survey of 20..." |
In a survey of 2000 student commuters, 112 said they got to school by means of train. Find the 95 percent confidence interval for the true proportion of students who get to school by train. Find the upper and lower limit of the 95 percent confidence interval. Round answers to the nearest hundredth. |
Multiple Choice:
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164) Problem #PRAFSZF "PRAFSZF - 164057 - In a study of &nb..." |
In a study of 1000 drivers, 745 said they drive at least 5 miles over the speed limit while driving on the highway. Find the 90 percent confidence interval for the true proportion of drivers who drive at least 5 miles over the speed limit while on the highway. Find the upper and lower limit of the 90 percent confidence interval. Round answers to the nearest hundredth. |
Multiple Choice:
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165) Problem #PRAFSUM "PRAFSUM - 163907 - In a study of 500..." |
In a study of 500 college seniors, 433 said they recieved a higher test score by using flashcards instead of conventional studying methods. Find the 98 percent confidence interval for the true proportion of college seniors who recieve higher test grades with the use of test scores. Find the upper and lower limit of the 98 percent confidence interval. Round answers to the nearest hundredth. |
Multiple Choice:
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166) Problem #PRAFS7A "PRAFS7A - 164238 - Given the SRS bel..." |
Given the SRS below, find the point estimate. {0, 20, 15, 13, 29, 7, 26, 32, 33, 35, 21} Round to the nearest hundredth place. |
Algebraic Expression:
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Hints: |
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167) Problem #PRAFS65 "PRAFS65 - 164233 - Given an SRS of {..." |
Given an SRS of {20, 15, 32, 8, 19, 16, 22, 31, 10, 7, 14} and given σ = 2.59 Find the margin of error when using 1.960 for z* . (Round to the nearest hundredth) |
Algebraic Expression:
|
Hints: |
|
1.960(2.59/√11) = 1.53 |
168) Problem #PRAFS68 "PRAFS68 - 164236 - Find a 90% confid..." |
Find a 90% confidence interval if the mean from and SRS = 10, n=15, and σ = 2.5. Round to the nearest hundredth place. |
Algebraic Expression:
|
Hints: |
Mean +/- z*(σ/√n) 10 +/- 1.645(2.5/√15) = (8.94,11.06) |
169) Problem #PRAFSWF "PRAFSWF - 163964 - A study was done ..." |
A)
A study was done to see how many colleges students applied to. The results of the 30 students are shown: 10, 6, 8, 9, 4, 3, 12, 6, 7, 10, 9, 10, 5, 9, 15 9, 7, 12, 6, 5, 4, 10, 12, 8, 11, 8, 14, 7, 6, 4 What is the margin of error for a 95% confidence level?
|
Algebraic Expression:
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Hints: |
Calculate the standard deviation on your calculator. |
B)
What is the 95% confidence interval? |
Multiple Choice:
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Hints: |
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170) Problem #PRAFSW8 "PRAFSW8 - 163988 - In a sample of 3,..." |
In a sample of 3,000 people, 2,450 said that they had 3 or more cars in their family. Knowing this, find the 98% confidence level. |
Multiple Choice:
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Hints: |
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171) Problem #PRAFSWE "PRAFSWE - Term 3 Project" |
A)
Suppose you are flipping a coin. We assume that the probability of getting a head is .5 and a tail is .5 as well. Let p = the probability of getting a head. You flip a coin 100 times and find that p is .47. The standard deviation of the population is .1. Is that evidence that p is not equal to .5? Let's start by finding H0 and Ha. |
Multiple Choice:
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B)
When we approximate p-hat normally, what is the mean? |
Algebraic Expression:
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Hints: |
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C)
What is the standard deviation of the normal approximation? |
Algebraic Expression:
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Hints: |
|
D)
What is the p-value? Round to 4 decimal places. |
Algebraic Expression:
|
E)
If our alpha level is .01, is the coin fair? |
Multiple Choice:
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172) Problem #PRAFS3A "PRAFS3A - 164114 - You use t* when you:" |
You use t* when you: |
Multiple Choice:
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173) Problem #PRAFS3B "PRAFS3B - 164115 - You use z* when you:" |
You use z* when you: |
Multiple Choice:
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174) Problem #PRAFS3C "PRAFS3C - 164116 - It is more likely..." |
It is more likely that you will: |
Multiple Choice:
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175) Problem #PRAFS3D "PRAFS3D - 164117 - As the degrees of..." |
As the degrees of freedom increase, |
Multiple Choice:
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176) Problem #PRAFSUZ "PRAFSUZ - Confidence Intervals " |
A)
Suppose the mean IQ is 100. There are 49 students chosen at random with a mean of 104.5 and a standard deviation of 15. What is the z-score? |
Algebraic Expression:
|
B)
What is the p-value? Round to the nearest thousands. |
Algebraic Expression:
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177) Problem #PRAFSU2 "PRAFSU2 - Confidence Intervals" |
We reject the null if the p-value is... |
Multiple Choice:
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178) Problem #PRAFSU3 "PRAFSU3 - Confidence Intervals" |
A)
Suppose the mean for the SAT is 1600. In a random sample of 81 students, the mean is 1611 with a standard deviation of 50. The significance level is 0.05. The principal claims that the students have a higher mean for the SAT. What is the z-score? |
Algebraic Expression:
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B)
What is the p-value? Round to the nearest thousands. |
Algebraic Expression:
|
C)
Is the principal correct? |
Multiple Choice:
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179) Problem #PRAFS2E "PRAFS2E - 164087 - An inspector is m..." |
An inspector is measuring the weight of meat at a restaurant for house burger. He measures 134 burgers and comes out with an average weight of 0.76 pounds and a standard deviation of 0.08 pounds. What is the 99% confidence level of the weight of all of the burgers made at the restaurant? |
Multiple Choice:
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180) Problem #PRAFS2J "PRAFS2J - 164091 - What is the t* va..." |
A)
What is the t* value for a sample size of 67 and a 95% confidence level? |
Multiple Choice:
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B)
What is the z* value for a 90% confidence level? |
Multiple Choice:
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181) Problem #PRAFS2Q "PRAFS2Q - 164096 - A man measures th..." |
A)
A man measures the size of fish the he finds while fishing over the corse of the year. He caught 170 fish and on average they weigh 9.1 pounds with a standard deviation of 1.7 pounds. What is the 90% margin of error in the fish's weight? |
Multiple Choice:
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B)
What is the estimated size of the mean population of fish with the above information given? |
Multiple Choice:
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182) Problem #PRAFS5D "PRAFS5D - 164179 - John has a sample..." |
A)
John has a sample of 41 dogs. The average amount of food each dog eats is 1lbs a day. The standard deviation of the sample is .05lbs. What is the upper bound assuming a 95% confidence interval? (3 decimal places) |
Algebraic Expression:
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B)
What is the lower bound of the previous problem assuming a 95% confidence interval? (3 decimal places) |
Algebraic Expression:
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183) Problem #PRAFS5K "PRAFS5K - 164185 - John has a sample..." |
A)
John has a sample of 100 children. The average test score of these children is a 75. The standard deviation is 5. what is the margin of error assuming there is a 95% confidence interval?(3 decimal places) |
Algebraic Expression:
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B)
What is the upper and lower bound of the previous problem? |
Multiple Choice:
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184) Problem #PRAFS5R "PRAFS5R - 164190 - The probability o..." |
A)
The probability of choosing a male randomly in a mall is .43. John randomly chooses at a mall 100 times. What is the margin of error of John if there is a 90% confidence interval? (4 decimal places) |
Algebraic Expression:
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B)
What is the upper bound assuming a 90% confidence interval? |
Algebraic Expression:
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C)
What is the lower bound assuming there is a 90% confidence interval? |
Algebraic Expression:
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185) Problem #PRAFS4T "PRAFS4T - 164161 - Which of the form..." |
A)
Which of the formulas represents accurately the Confidence Interval ? |
Multiple Choice:
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B)
The following is a sample of 15 works and the amount they were paid in one day. Assume the standard deviation is 10. 138 127.3 139.1 115.6 113 130.4 132.5 130.2 140.7 111.7 109.7 105.5 118.9 134.8 109.6 Assume a union rep wants to sample 60 workers to get abetter understanding. What is the new 95% Confidence interval for the mean pay ? |
Multiple Choice:
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C)
A senior praefect is at his post and sees 7th graders running. He claims the speed of the 7th grader averges 10 mph. Imagine if a sample of 33 7th graders yields a mean of 7 mph and a standard deviation of 1.5. What is the H0 and HA ? |
Multiple Choice:
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D)
What is the p-value for the problem ? |
Exact Match (case sensitive):
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E)
Do we reject or fail to reject the senior's claim ? |
Multiple Choice:
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186) Problem #PRAFS42 "PRAFS42 - 164168 - If i sit outside ..." |
A)
If i sit outside and measure the temperature for 6 consecutive days and get temperatures of 72.5 , 71.7 , 73.1, 72.2 , 70.9, and 70.5 mean- 71.8 sd - .02 what would be the distribution? |
Multiple Choice:
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B)
What is the confidence interval for the population at a 95% confidence interval? Answer - x.xx,x.xx |
Algebraic Expression:
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187) Problem #PRAFS5G "PRAFS5G - 164182 - the sample distri..." |
the sample distribution is N(?,?) |
Multiple Choice:
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188) Problem #PRAFS5N "PRAFS5N - 164187 - True or False : T..." |
True or False : The larger the sample size the smaller margin of error |
Multiple Choice:
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189) Problem #PRAFS5S "PRAFS5S - 164191 - Mean - 96 Sd- 2 S..." |
Mean - 96 Sd- 2 Sample size - 10 95% Confidence interval = xx.x,xx.x |
Algebraic Expression:
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190) Problem #PRAFTTY "PRAFTTY - 164848 - Ch. 10 #1" |
What does Ho and Ha represent respectively? |
Multiple Choice:
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191) Problem #PRAFTUR "PRAFTUR - Ch. 10 #2-5" |
A)
A shoemaker claims that their shoes fit more than 95% of the
population comfortably. A study was taken on 100 customers, and 93% of the
population thought the shoes fit comfortably, with a standard deviation of
10.2%. Using the 5% significance interval, can we prove the shoemaker’s claim? First off, identify the null hypothesis and alternative hypothesis. |
Multiple Choice:
|
B)
What is the resulting z-value? |
Multiple Choice:
|
C)
What is the correct p-value? Please note that Ha: μ
> 95. |
Multiple Choice:
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D)
What can we thus conclude? |
Multiple Choice:
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192) Problem #PRAFH3G "PRAFH3G - 156432 - Chapter 10.1-10.2 Question" |
A)
Below are is a list of how many cigarettes 20 random people said they smoke in a day: 0 0 2 4 4 5 5 5 6 7 8 9 11 12 15 18 22 24 25 32 What is the distrubtion of the data? |
Multiple Choice:
|
B)
Does this meet the 3 conditions required? What are they and how is it show that it is met? |
Ungraded Open Response: |
C)
What is the mean? Answer to the tenths. |
Algebraic Expression:
|
D)
What is the standard deviation of the sample? |
Algebraic Expression:
|
E)
What is the standard error at 95% confidence? Answer to the nearest hundreds. |
Algebraic Expression:
|
193) Problem #PRAFS6G "PRAFS6G - 164213 - A random sample o..." |
A)
A random sample of people were surveyed in order to find the average of number of tagged photos a person on facebook has. Below are the results: 1433 394 567 1089 234 567 789 675 345 234 1217 576 696 309 129 435 818 881 765 361 What is x-bar? Round to the hundredth place. |
Algebraic Expression:
|
Hints: |
|
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B)
If you were to construct a 95% confidence interval, what would the margin of error be? Round to the tenth place. |
Algebraic Expression:
|
Hints: |
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C)
What is the lower limit? Round to the hundredth place. |
Algebraic Expression:
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Hints: |
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194) Problem #PRAFS52 "PRAFS52 - 164199 - Before a new movi..." |
A)
Before a new movie comes out in theaters, a free screening is usually shown in selected theaters beforehand in order to see how well the movie will probably do. Recently, a free screening was shown to and audience of 345 people. Out of the 345, 198 gave a positive review. Construct a 99% confidence interval. Find the lower limit. Round to the hundredth place. |
Algebraic Expression:
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Hints: |
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B)
What is the upper limit? Round to the hundredth place. |
Algebraic Expression:
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Hints: |
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195) Problem #PRAFS4U "PRAFS4U - 164162 - Crop researchers ..." |
A)
Crop researchers planted a new type of corn in 60 plots of land. They obtained a mean yield of bushels per acre of 123.8 bushels per acre. Assume that the standard deviation of the population, or σ, is 10 bushels per acre. Find the 95% confidence interval for the mean yield μ. Round your answer to the nearest hundredth. Your answer should contain two numbers, representing the interval, with "to" between the numbers. |
Algebraic Expression:
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Hints: |
confidence interval = x-bar + or - (z*)(σ / the square root of n) |
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confidence interval = 123.8 + or - (1.960)(10/square root of 60) |
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B)
Using the same information, find the 99% confidence interval. Round your answer to the nearest hundredth. Your answer should contain two numbers, representing the interval, with "to" between the numbers. |
Algebraic Expression:
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Hints: |
Because you know the standard deviation σ, use the following equation to determine the confidence interval: confidence interval = x-bar + or - (z*)(σ / the square root of n) |
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Plug these numbers into the equation. confidence interval = 123.8 + or - (2.576)(10/square root of 60) |
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C)
Suppose that the same crop researchers obtained the same x-bar from a sample of 15 plots instead of a sample of 60 plots. Assume that the standard deviation of the population, or σ, is still 10 bushels per acre. Find the 90% confidence interval for the mean yield μ. Round your answer to the nearest hundredth. Your answer should contain two numbers, representing the interval, with "to" between the numbers. |
Algebraic Expression:
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Hints: |
Because you know the standard deviation σ, use the following equation to determine the confidence interval: confidence interval = x-bar + or - (z*)(σ / the square root of n) |
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Plug these numbers into the equation. confidence interval = 123.8 + or - (1.645)(10/square root of 15) |
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D)
Is the margin of error for the sample of 60 plots larger or smaller than the margin of error for the sample of 15 plots? |
Multiple Choice:
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Hints: |
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E)
Would the 95% and the 99% intervals for the sample size of 15 plots be narrower or wider than those for the sample size of 60? |
Multiple Choice:
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196) Problem #PRAFS4Q "PRAFS4Q - 164158 - A SRS of 20 NBA t..." |
A)
A SRS of 20 NBA teams is collected. The sample has a mean of 35 free throws per game and a standard deviation of 4. We are going to calculate the 95% confidence interval of the mean number of free throws per game. What is the number that represents the point estimate? |
Algebraic Expression:
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B)
What 3 conditions must be met before constructing a confidence interval for mu? |
Ungraded Open Response: |
C)
What is t-star for a sample size of 20 and a 95% confidence interval. Do not round. |
Algebraic Expression:
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D)
Calculate the margin of error for this same problem. Remember the equation t*(s/sqrt n). |
Algebraic Expression:
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E)
Calculate the lower limit |
Algebraic Expression:
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F)
Calculate the upper limit |
Algebraic Expression:
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197) Problem #PRAFS34 "PRAFS34 - 164139 - What are the thre..." |
A)
What are the three conditions for inference about a proportion? |
Ungraded Open Response: |
Hints: |
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B)
In Russia 1048 people attend a high school. A SRS of 692 of the students when asked if they liked the atmosphere of their high school responded "Yes". Give a 95% confidence interval for the proportion of students who approve of the atmosphere. |
Multiple Choice:
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Scaffold:
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Scaffold:
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C)
900 people in Massachusetts have their car stolen every week. One study examined the records of 1711 of these reported stealings and discovered that 542 of these people had their cars stolen by someone they knew. Give a 95% confidence interval for p. |
Multiple Choice:
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Hints: |
www.dimensionresearch.com/resources/calculators/conf_prop.html |
D)
In the following situation state the null hypothesis (H0) and the alternative hypothesis (HA). In 2010, it usually took an fire truck 10 minutes on average to respond to a call. This year researchers suspect a lower average response time. |
Multiple Choice:
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E)
The amount of packages of OREO cookies sold at grocery stores is normally distributed with a mean of 345 packages per week and a standard deviation of 33 packages per week. Grocery store managers predict that the number is in fact higher. Therefore, a SRS is taken of 65 grocery stores and the mean (x-bar) of t the study is 355. Is the result statistically significant at the .05 level? |
Multiple Choice:
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198) Problem #PRAFS5A "PRAFS5A - 164176 - Find the 95% conf..." |
A)
Find the 95% confidence interal for the mean of the boiling point of water from a sample size of 32 with a mean of 212.5 and a standard deviation of 1.2. Give the lower limit round to the hundredths. |
Algebraic Expression:
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B)
Give the upper limits and round to the hundredths. |
Algebraic Expression:
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199) Problem #PRAFS47 "PRAFS47 - 164173 - What is a confide..." |
What is a confidence interval? |
Ungraded Open Response: |
200) Problem #PRAFS43 "PRAFS43 - 164169 - Suppose we want t..." |
Suppose we want to estimate the average weight of men in Boston. We draw a radom sample of 1,000 men and weigh them. The average wight of a male in Boston is 180 pounds and the standard deviation of the sample is 30 pounds. What is the 95% confidence interval. |
Multiple Choice:
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201) Problem #PRAFUEC "PRAFUEC - 165418 - Confidence Intervals" |
A)
You work for a phone company and you are planning a survey to see what fraction of people would buy your phone service if you offered free nights and weekends. You guess that about 20% of people would accept. In order to convince your boss to offer this promotion, you need a 90% confidence interval within 4%. (copy this into your notebook) Does this problem the format for Confidence Interval testing? |
Multiple Choice:
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B)
Referring to the previous problem, what type of setting is this? |
Exact Match (case sensitive):
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Hints: |
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C)
Again referring to the original problem, decide how many possible clients you must survey. |
Algebraic Expression:
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Hints: |
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D)
15 students were randomly selected from a grade of science students. For the 15 students, each one's Midyear Exam score was taken. The mean score was 85.5 and the standard deviation was 10 points. Find a 90% Confidence Interval for the mean test score for all students. (Assume that this is Normally Distributed). Round to the nearest hundreth. |
Algebraic Expression:
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Hints: |
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E)
You work for the City of Boston and you want to learn a bit about the public transportation system from kids who take it everyday. You surveyed 200 students and 148 of them say that their bus has been late ≥ 3 times this year. Find the 90% Confidence Interval. Round to the nearst hundreth. |
Algebraic Expression:
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Hints: |
90% C.I. goes with 1.645 on the t-table. |
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202) Problem #PRAFSUY "PRAFSUY - Confidence Intervals" |
What should you always try to do? |
Multiple Choice:
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203) Problem #PRAFTWF "PRAFTWF - 164925 - You are goin..." |
A)
You are going to find the 90% confidence interval. A sample of 300 students is taken to determine the average GPA of the senior class. The mean on the sample distribution is 3.12 with a standard deviation of 5. What is x-bar? |
Exact Match (case sensitive):
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B)
What is the margin of error? Round answer two decimal places. |
Exact Match (case sensitive):
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C)
What is the 90% confidence interval? Round answer two decimal places. |
Multiple Choice:
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204) Problem #PRAFUE5 "PRAFUE5 - 165442 - Sarah wants to fi..." |
A)
Sarah wants to find the average height of a cover girl model. She takes a sample and records the following height in inches: 70.92, 71.76, 72, 73.32, 75.6. What is the mean of the sample distribution? |
Exact Match (case sensitive):
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B)
What is the 99% confidence interval? |
Multiple Choice:
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205) Problem #PRAFUFE "PRAFUFE - 165451 - A study is conduc..." |
A study is conducted in a neighborhood to better understand the types of recreational activities. 100 individuals are selected at random and surveyed. It is known that 2,500 children, 7,000 adults and 500 elderly live in the neighborhood. Therefore, the researchers decide to choose the previous sample using stratified sampling as it is known that the recreations of the inhabitants change with age. Knowing this, determine the sample size for each stratum. |
Algebraic Expression:
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206) Problem #PRAFUFA "PRAFUFA - 165447 - A sample of stude..." |
A sample of students from an introductory psychology class were polled regarding the number of hours they spent studying for the last exam. All students anonymously submitted the number of hours on a 3 by 5 card. There were 24 individuals in the one section of the course polled. The data was used to make inferences regarding the other students taking the course. There data are below:
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Algebraic Expression:
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207) Problem #PRAFUE6 "PRAFUE6 - 165443 - A university want..." |
A)
A university wants to know more about the knowledge of students regarding international events. The are concerned that their students are uninformed in regards to new from other countries. A standardized test is used to assess students knowledge of world events (national reported mean=65, S=5). A sample of 30 students are tested (sample mean=58, Standard Error=3.2). What is the lowest value of the confidence interval? |
Algebraic Expression:
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B) |
Algebraic Expression:
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208) Problem #PRAFUE3 "PRAFUE3 - 165440 - A sample of Alzhe..." |
A)
A sample of Alzheimer's patients are tested to assess the amount of time in stage IV sleep. It has been hypothesized that individuals sufferering from Alzheimer's Disease may spend less time per night in the deeper stages of sleep. Number of minutes spent is Stage IV sleep is recorded for sixty-one patients. The sample produced a mean of 48 minutes (S=14 minutes) of stage IV sleep over a 24 hour period of time. Compute a 95 percent confidence interval for this data. What does is the minimum value of the confidence interval? |
Algebraic Expression:
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B)
What is the maximum confidence interval value (for the previous data)? |
Algebraic Expression:
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209) Problem #PRAFUVU "PRAFUVU - Confidence Interval 2" |
In a national survey, the average GPA amongst high school seniors was 2.7 with a standard deviation of .4. Assuming there is a 95% confidence level, what is the margin of error for this survey? |
Multiple Choice:
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210) Problem #PRAFUVZ "PRAFUVZ - Confidence Interval 3" |
The Boston Globe selected a random sample of 1,600 readers from their list of 100,000 subscribers. They asked whether the paper should increase its coverage of local news. Forty percent of the sample wanted more local news. What is the 99% confidence interval for the proportion of readers who would like more coverage of local news? |
Multiple Choice:
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211) Problem #PRAFUV2 "PRAFUV2 - Confidence Interval 4" |
The Cartoon Network conducts a survey to determine viewer attitudes toward Batman. They randomly select 400 boys and 300 girls to participate in the study. Forty percent of the boys say that Batman is their favorite character, while only to thirty percent of the girls said Batman was their favorite. What is the 90% confidence interval for the difference in attitudes toward Batman? (A) 0 to 20 percent more boys prefer Superman (B) 2 to 18 percent more boys prefer Superman (C) 4 to 16 percent more boys prefer Superman (D) 6 to 14 percent more boys prefer Superman (E) None of the above |
Multiple Choice:
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212) Problem #PRAFUV3 "PRAFUV3 - Confidence Interval 5" |
A)
An inventor has developed a new, energy-efficient lawn mower engine. He claims that the engine will run continuously for 5 hours (300 minutes) on a single gallon of regular gasoline. Suppose a simple random sample of 50 engines is tested. The engines run for an average of 295 minutes, with a standard deviation of 20 minutes. Test the null hypothesis that the mean run time is 300 minutes against the alternative hypothesis that the mean run time is not 300 minutes. Use a 0.05 level of significance. (Assume that run times for the population of engines are normally distributed.) What is the proper hypothesis for this problem? |
Multiple Choice:
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B)
Find the P- Value based on the hypothesis. |
Algebraic Expression:
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C)
Based on the P-Value you got in the previous problem we _____________. |
Multiple Choice:
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213) Problem #PRAFV58 "PRAFV58 - 167088 - Researchers often..." |
A)
Researchers often claim that 95% of Americans will experience an automobile accident at some point in their lives. A recent study set out to claim that it was in fact less. They asked 50 people whether they had been in an automobile accident and found that 45 had. The significance level used in the study was 5%. What was the alternative hypothesis of the study? |
Multiple Choice:
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B)
Referring to the previous problem's information, find the standard deviation. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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C)
Find the Z score for this proportion. Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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D)
Given the Z-score and the significance level, would the researchers reject the null hypothesis? |
Multiple Choice:
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E)
Do the researchers have sufficient evidence to say that less than 95% of people will experience an automobile accident in their lives? |
Multiple Choice:
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214) Problem #PRAFWSX "PRAFWSX - 167699 - Obama predicted t..." |
A)
Obama predicted that less than 42% of all Americans would consider his proposed programs for the country too liberal. A recent CNN poll of 1023 voters shows that 46% of the voters consider his programs too liberal. Using this information, what is the alternative hypothesis? |
Multiple Choice:
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B)
Using the information from the previous problem, find the standard deviation. |
Algebraic Expression:
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C)
Using the information from the problem, find the z-score. Round to the nearest hundredth. |
Algebraic Expression:
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D)
At the the 95% significance level, what is the conclusion? |
Multiple Choice:
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Hints: |
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.0028<.05 |
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E)
Is there sufficient information to conclude that less than 95% of voters do not support Obama's programs? |
Multiple Choice:
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215) Problem #PRAFW8R "PRAFW8R - 168127 - A researcher beli..." |
A)
A researcher believes that
in recent years women have been getting taller. She knows that 10 years ago the
average height of young adult women living in her city was 63 inches. The
standard deviation is unknown. She randomly samples eight young adult women
currently residing in her city and measures their heights. The following data
are obtained: [64, 66, 68, 60, 62, 65, 66, 63.] α= .05 What is t? Round to the nearest hundredth |
Algebraic Expression:
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Hints: |
t = X −μ0 = 64.25−63 =1.387 sX 0.901 |
B)
Refer to the previous problem. What is the p-value? round to the nearest 3rd decimal place. |
Algebraic Expression:
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C)
Refer to the previous problems? Should the researcher reject the null or fail to reject? |
Multiple Choice:
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D)
Refer to the previous problem. What is the probability of Type 1 error occurring? |
Algebraic Expression:
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Hints: |
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E)
Refer to the previous problem. At what value on the density curve would the researcher be able to reject the null hypothesis? Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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F)
Refer to the previous problems If the researcher did reject the null hypothesis, but the actual mean was less than 64.49, what type of error would that be? |
Multiple Choice:
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216) Problem #PRAFXX5 "PRAFXX5 - 168821 - A High School stu..." |
A)
A High School student playing basketball wants to know how many people of the next random 50 people who walk down the street next to his court can make a basket. His friend believes half the people will make it (the null hypothesis). What is the proportion of people who make the basket? |
Algebraic Expression:
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B)
Refer to the previous problem. What is the P value? |
Algebraic Expression:
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C)
Refer to the previous problem. Based on an α of .05, can we reject the null hypothesis, yes or no? |
Multiple Choice:
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217) Problem #PRAGAHF "PRAGAHF - 178968 - x-bar of a sample..." |
A)
x-bar of a sample: 5 sd of a sample: 10 population size: 100 what equation would you use for this situation to find the upper bound of a .95 CI? |
Multiple Choice:
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B)
Solve for the upper bound of a .95 CI with the given data above. |
Algebraic Expression:
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218) Problem #PRAGAHK "PRAGAHK - 178972 - Which of the foll..." |
Which of the followign is true about the relationship between sample size and confidence interval? |
Multiple Choice:
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219) Problem #PRAGAHN "PRAGAHN - 178974 - A .95 confidence ..." |
A .95 confidence interval tells us the probability that the interval will capture the true parameter value in repeated samples. |
Multiple Choice:
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220) Problem #PRAGAHP "PRAGAHP - 178975 - X-bar is a..." |
X-bar is always captured by the confidence interval |
Multiple Choice:
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221) Problem #PRAGAHQ "PRAGAHQ - 178976 - Mu is always incl..." |
Mu is always included in the confidence interval |
Multiple Choice:
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