1) Problem #PRAF66C "PRAF66C - 175741 - Which one of the ..." |
A)
Which one of the following accurately shows the one-sample z statistic ? |
Multiple Choice:
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B)
If the Z were to be 1.7, and the distribution was two sided, what would the P-value be ? |
Exact Match (case sensitive):
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2) Problem #PRAF66E "PRAF66E - 175743 - Pick all of the a..." |
A)
Pick all of the applicable. Which are the conditions in order to use the Inferecne for proportions ? |
Check All That Apply:
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B)
Now knowing the conditions to use the SRS test, is the test suitable for the following? The Headmaster believes that 99% of seniors have been tardy at least once in their time at BLS. The Stats professor gets 200 of the seniors (out of 15,000 to test the claim. Ho=99% |
Multiple Choice:
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3) Problem #PRAF66F "PRAF66F - 175744 - If a sample was c..." |
A)
If a sample was conducted on 15 students about Orange Juice and Apple Juice and the t value was 1.82, what was the degress of freedom ? |
Exact Match (case sensitive):
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B)
Is that t-value significant at the 5% level? |
Multiple Choice:
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4) Problem #PRAF7HP "PRAF7HP - 176092 - If you have an X-..." |
A)
If you have an X-bar of 122, a mu of 125, a sample size of 75, and a SD of 15. Find Z: |
Algebraic Expression:
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Hints: |
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B)
What is the p-value? |
Algebraic Expression:
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C)
Do you reject or fail to reject the null? |
Multiple Choice:
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5) Problem #PRAF7HR "PRAF7HR - 176094 - Assume P-hat is ...." |
A)
Assume P-hat is .5, p is .55, and there is an SRS of 50, find Z: |
Algebraic Expression:
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Hints: |
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B)
What is the p-value? |
Algebraic Expression:
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C)
What is the conclusion? |
Multiple Choice:
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6) Problem #PRAF7HS "PRAF7HS - 176095 - Assume x-bar is 4..." |
A)
Assume x-bar is 45, mu is 50, SD of the sample is 15, and the SRS of size 75. Find t: |
Algebraic Expression:
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Hints: |
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B)
What is the Degrees of freedom? |
Algebraic Expression:
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Hints: |
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C)
What is the p-value? |
Multiple Choice:
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D)
What is the conclusion? |
Multiple Choice:
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7) Problem #PRAF6M5 "PRAF6M5 - 175238 - Bottles of a part..." |
A)
Bottles of a particular brand of water is supposed to have 300 milliliters (mL) of nutrients. The amount varies from bottle to bottle because the precision of the machines is not too precise. The distribution is normal with a standard deviation σ = 3 mL. An inspector of the company suspects that the company is under-filling the bottles. The inspector took a sample of six bottles and the results are below. 299.4, 297.7, 301, 298.9, 300.2, 297 Is this convincing evidence that the mean contents of the water bottles is less than the supposed 300 mL? |
Algebraic Expression:
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B)
A report showed that the mean weight for young women is 128 pounds and the standard deviation is 15. A weight management company looks at the records of 72 clients and finds that the mean weight is 126.07. Is this evidence that the clients have a different mean weight from the general population? |
Algebraic Expression:
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8) Problem #PRAF6S5 "PRAF6S5 - 175393 - In 1998, 7,741 st..." |
A)
In 1998, 7,741 students identified themselves as a frequent smoker (from an SRS of 140 colleges and 17,592 students). Is this strong evidence that more than 40% of college students were frequent smokers in 1998? |
Algebraic Expression:
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Scaffold:
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B)
It is known that whena coin is balanced, half of the results should be heads when flipped. A man tossed a coin 4040 times and got 2048 heads. Is this evidence that the man's coin was not balanced? |
Algebraic Expression:
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9) Problem #PRAF6S6 "PRAF6S6 - 175394 - The mean length o..." |
A)
The mean length of certain construction lumber is supposed to be 8.5 feet. A random sample of 81 pieces of such lumbers gives a sample mean of 8.3 feet and a sample standard deviation of 1.2 feet. A builder claims that the mean of the lumber is different from 8.5 feet. Does the data support the builder's claim at alpha = 0.05? |
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B)
Local cookie bakers test new recipes for loss of sweetnes during storage. Tasters rate the sweetness before and after storage. THe data below shows the sweetness loss found by 10 tasters for a new cookie recipe: 2.3, 1.1, 1.2, 1.3, 2.2, -0.4, 2, 0.7, 0.4, 2 Is this strong evidence that the cookie lost sweetness? |
Algebraic Expression:
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10) Problem #PRAF7SP "PRAF7SP - " |
Calculate the z-value for this parameter where σ is 5, x-bar is 74, μ is 76 and the sample size is 50. Round to nearest hundredth. |
Multiple Choice:
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11) Problem #PRAF7SQ "PRAF7SQ - 176341 - Calculate the z-v..." |
Calculate the z-value for this parameter. σ is 8, μ is 52, x-bar is 54, and sample size is 75. Round to nearest hundredth. |
Multiple Choice:
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12) Problem #PRAF7SR "PRAF7SR - 176342 - Calculate the z-v..." |
Calculate the z-value for this proportion. P-hat is 9 and P0 is 10. The probability is %30 and the sample size is 10. |
Multiple Choice:
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13) Problem #PRAF7SS "PRAF7SS - 176343 - Calculate the z-v..." |
Calculate the z-value for this proportion. P-hat is 8, P0 is 9, the probability is %40 and the sample size is 70. |
Multiple Choice:
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14) Problem #PRAF7ST "PRAF7ST - 176344 - Calculate the one..." |
Calculate the one-sample t-statistic: X-bar is 34, μ is 33, the standard deviation of the sample is 4.5 and the sample size is 50. Round to nearest hundredth. |
Multiple Choice:
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15) Problem #PRAF65S "PRAF65S - z-population sigma known #2" |
You are running a medical test that has an equal chance of being either above or below the expected mean of 50 '0/00' (parts per thousand), with a standard deviation of 17 '0/00.' You run 72 tests and find that the mean of the SRS is actually 53.2. Is there significant evidence (at the alpha = .1 level) that the mean does not equal 50? |
Multiple Choice:
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16) Problem #PRAF65T "PRAF65T - 175724 - z-test proportion #1" |
When flipping a coin, one would expect that the coin would land heads .5. When you conduct a sample test of 1000 flips, you find that the SRS mean is .53. Is there significant evidence at the .025 level that the coin is unfair? |
Multiple Choice:
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17) Problem #PRAF65U "PRAF65U - z-test proportion #2" |
You are conducting a chemical experiment to determine the proportion of times that a reaction goes to completion. You have theorized that it will go to completion approximately .437. After 42 tests, you find, however, that the sample proportion is .491. Is there significant evidence at the .01 level to recalculate your theory? |
Multiple Choice:
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18) Problem #PRAF65V "PRAF65V - t-test s known" |
You have a set of test scores with a population mean of 87, but you do not know sigma. For 150 tests, s is approximately 3.4 and x-bar is 81. Is there significant evidence at the .05 level to suggest that the mean is lower than 87? |
Multiple Choice:
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19) Problem #PRAF7MD "PRAF7MD - 176176 - We want to compar..." |
We want to compare the average number of free throws of the Bucks to the entire NBA. Many seem to think that the Bucks have a lower free average per game than the NBA. Suppose the free throw average per game for the NBA is 15. We gather the data from 20 games and find that the average for the Bucks is 18. The population standard deviation is 4. Do we have evidence to prove that the Bucks free throw average per game is higher than the NBA's? (The significance value is .05) |
Multiple Choice:
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Hints: |
Null: mu = 15 Alternative: mu > 18 |
z = (x-bar - mu)/(σ/√n) Z = -3.35 p = .0004 p<α |
20) Problem #PRAF7SW "PRAF7SW - 176347 - Find the confiden..." |
Find the confidence interval if 200 out of 1500 kids have diabetes. Calculate using a 99% confidence interval. Z* = 2.576 Answer should be in the form of (x%, y%) x and y should be whole numbers. |
Algebraic Expression:
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Hints: |
Formula that should be used is p-hat +/- z*√((p-hat)(1-p-hat)/n) |
21) Problem #PRAF7XQ "PRAF7XQ - 176496 - It is believed th..." |
It is believed that 10% of men actively play tennis. Out of a sample of 3000 men, 247 admitted to playing tennis actively. Does this show strong evidence that less than 10% of men play tennis? |
Multiple Choice:
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Hints: |
Use the formula for z-score = (p-hat-p-null)/√(p-null(1-p-null)/n). |
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22) Problem #PRAF7XS "PRAF7XS - 176498 - A baseball analys..." |
A baseball analyst believes the average MLB ERA is greater than 4.5. Upon averaging 45 pitchers, an ERA of 4.62 was found. With a standard deviation of 0.5, what is the t-score. |
Algebraic Expression:
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Hints: |
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23) Problem #PRAF7JT "PRAF7JT - 176127 - 303 287 297 30..." |
303 287 297 301 299 290 Given the data set above, which is normally distributed with a standard deviation of sigma=3 and mu=300, what is z? Round to the nearest hundredths. |
Algebraic Expression:
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Hints: |
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24) Problem #PRAF7JU "PRAF7JU - 176128 - Sam tossed a coin..." |
A)
Sam tossed a coin 238 times. He got 115 heads. The null hypothesis is p=0.5. The alternative is two-sided (p does not equal 0.5). Given the following information, what is z? Round to the nearest hundredths. |
Algebraic Expression:
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Hints: |
-0.0168/0.0324 --> z=-0.52 |
B)
What is the p-value? |
Algebraic Expression:
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Hints: |
P-value= 0.603 |
25) Problem #PRAF7JV "PRAF7JV - 176129 - If p-hat is 0.506..." |
If p-hat is 0.5069, n=315, z* for a 95% confidence interval is 1.960, what is the confidence interval? |
Multiple Choice:
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26) Problem #PRAF7JW "PRAF7JW - 176130 - n=20 x-bar= 36.5 ..." |
A)
n=20 x-bar= 36.5 s= 3.2 Ho: mu=30 Ha: mu >30 Is this t or z? |
Multiple Choice:
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B)
What is t? Round to the nearest hundredths. |
Algebraic Expression:
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Hints: |
6.5/0.72 t with df of 19= 9.03 |
27) Problem #PRAF7SY "PRAF7SY - 176349 - A group of high s..." |
A)
A group of high school students are arguing about what the average IQ of a teenager is. After looking it up on Google, the students read that the average IQ for a teenager from age 13-19 is 110. They decide to conduct a test, and with some teachers, they test 100 teenagers and find out their IQ scores. The mean score is 109. Does this sample indicate good evidence that the mean IQ score for all teenagers is less than 110? Assume a standard deviation (sigma) of 16. a). State the null and alternative hypotheses. |
Ungraded Open Response: |
Hints: |
Ha: mu< 110 The mean IQ score for all teenagers is less than 110. |
B)
b). Find the p-value. Reject or fail to reject the null? |
Multiple Choice:
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28) Problem #PRAF7XV "PRAF7XV - 176501 - Farmer Simoneau i..." |
A)
Farmer Simoneau is observing his huge farm and notices that most of his cows have a spot on their left ear. He decides to call up some experts and see how often this occurs in nature. Some scientists conduct a survey of several farms across the United States. They survey 80,609 cows and of those, they found that 24,183 cows had a spot on their left ear. Considering this an SRS of 80,609 from the population of all cows in the U.S., does this show sufficient evidence that more than 25% of all cows have a spot on their left ear? a). State the null and alternative hypotheses. |
Ungraded Open Response: |
Hints: |
Ha: p>0.25 ;More than 25% of all cows in the U.S. have a spot on their left ear |
B)
b). Find the sample proportion of cows with spots on their left ears. |
Algebraic Expression:
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C)
c). Carry out the appropriate z-test and find the p-value. |
Algebraic Expression:
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Hints: |
z= 32.78 p-value = approximately 0 |
D)
d). Do we reject or fail to reject the null? |
Multiple Choice:
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29) Problem #PRAF7XW "PRAF7XW - 176502 - What are the cond..." |
A)
What are the conditions for inference about a proportion? (check all that apply) |
Check All That Apply:
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B)
Farmer Simoneau notices that he has many more female pigs than male pigs. He calls in the experts and they conduct a survey of many farms across the country. They survey 143000 pig and discover that of those pigs, 72648 of them are female. There is ideally supposed to be an equal proportion of male pigs to female pigs. Is there sufficient evidence to prove that there are more than 50% female pigs in the United States? a). Find the sample proportion of female pigs. |
Multiple Choice:
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C)
b). Calculate the z-statistic. |
Multiple Choice:
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30) Problem #PRAF7XY "PRAF7XY - 176504 - What are the cond..." |
What are the conditions for using a one-sample t-test? |
Check All That Apply:
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31) Problem #PRAF6TD "PRAF6TD - 175401 - The mean of a pop..." |
A)
The mean of a population is 450. You take a sample of 15 with a mean of 422. Suppose that σ is 36. What is z? Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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B)
Suppose the expected proportion of a population is .78. If you take a sample of 36 with a proportion of .69, what is the z? Round to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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C)
The mean of a population is 0. If the sample of 15 has a mean of 2.3, what is t*? Round to the nearest hundredth. |
Algebraic Expression:
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32) Problem #PRAF757 "PRAF757 - 176697 - A teacher was tol..." |
A)
A teacher was told by authorities that the standard deviation was 10 points, but was not told the mean of the population. The teacher wants to estimate the parameter μ of the score for the Biology final of a population of students. The teacher takes a sample of his class of 30 students and finds the mean (x-bar) to be 77 and a standard deviation of 13. Find the 95% confidence interval in (lowest, highest) form. |
Algebraic Expression:
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B)
Now imagine the same scenario, but with the teacher not knowing the population standard deviation. Find the 95% confidence interval. |
Algebraic Expression:
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Hints: |
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Scaffold:
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33) Problem #PRAF758 "PRAF758 - 176698 - A medical treatme..." |
A)
A medical treatment for athritis has been tested 144 times and has a success rate of 85%. What is the 99% confidence interval the population proportion in (lowest, highest) form rounded to the thousandths place? |
Algebraic Expression:
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Hints: |
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B)
Imagine the same situation, but instead of knowing the sample size, you know that the margin of error is 0.5 What is the sample size? Round up to the nearest whole number. |
Algebraic Expression:
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34) Problem #PRAF76B "PRAF76B - 176701 - A group of manufa..." |
A)
A group of manufacturers released a statment that said that the standard deviation of a screwdriver they produced was 12mm, but forgot to report the mean of the population. A student wants to estimate the parameter μ of the screwdrivers. The student takes a box of 100 screwdrivers and finds the mean (x-bar) to be 88mm and a standard deviation of 15mm. Find the 95% confidence interval in (lowest, highest) form. |
Algebraic Expression:
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B)
Now imagine the same scenario, but with the teacher not knowing the population standard deviation. Find the 95% confidence interval. |
Algebraic Expression:
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Hints: |
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35) Problem #PRAF76E "PRAF76E - 176704 - A calculator manu..." |
A calculator manufacturing plant has produced 500 calculatiors with a 97% rate of producing operational calculators. What is the 96% confidence interval the population proportion in (lowest, highest) form rounded to the thousandths place? |
Algebraic Expression:
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Hints: |
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36) Problem #PRAF755 "PRAF755 - 176695 - A research claime..." |
A)
A research claimed that male black athletes that participated in the Olympics were 6 feet or taller with standard deviation(sigma) of 0.27. For a sample of 100 male black atheletes in the Olympics, their mean height were 5.8 feet. Find the p-value and round to the nearest hundredth. |
Algebraic Expression:
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B)
At alpha = 0.01, what is your conclusion? |
Multiple Choice:
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37) Problem #PRAF76N "PRAF76N - 176711 - Employees going t..." |
A)
Employees going to work 5 minutes early received a bonus of $5 just for being at work. And then there are the employees who just come in on-time or late. For a sample of 50 employees who came in on-time or late, the bonus was $3 just for being at work. Based on prior experience, it is safe to assume sigma = $7. What is the p-value? Round to nearest hundredth. |
Algebraic Expression:
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B)
At a = 0.05, what is your conclusion? |
Multiple Choice:
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38) Problem #PRAF756 "PRAF756 - 176696 - A research s..." |
A)
A research study claims that 9 out of 10 dentists recommend Colgate's Prevident 5000 for their patients with cavities. To test this claim, a random sample of 100 dentists is obtained. Of these 100 doctors, 82 indicated that they recommend Colgate's Prevident 5000. Is this claim accurate? Use alpha = 0.05 First, what is the z-value you get? |
Multiple Choice:
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B)
What is your conclusion? |
Multiple Choice:
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39) Problem #PRAF76A "PRAF76A - 176700 - A survey claims t..." |
A)
A survey claims that 8 out of 10 personal trainers recommend Nike brand running shoes for people looking to enhance their performance skills. To test this claim, a random sample of 50 personal trainers is obtained. Of these 50 personal trainers, 39 supported this claim. Is this claim accurate? Use alpha = 0.05 First, what is the z-value you get? Round to the nearest hundredth. |
Algebraic Expression:
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B)
What is your conclusion? |
Multiple Choice:
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40) Problem #PRAF76D "PRAF76D - 176703 - A survey claimed ..." |
A)
A survey claimed that the mean of a pidgeon's life span was at least 9 years. A survey of 85 bird scientists reported that they found a mean life span of 7.27 years with a standard deviation of 6.38. (s = 6.38) Use a = 0.01. First, find the p-value. Round to nearest hundredth. |
Algebraic Expression:
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B)
What is your conclusion? |
Multiple Choice:
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41) Problem #PRAF76W "PRAF76W - 176719 - Z test for a popu..." |
Z test for a population mean A report by New York Times claims that an average teenager spends 2 hours on homework. 30 BLS students were surveyed, and the average time the group spends on homework is 4.4 hours. Is this good evidence that this sample differs from the average time spent on homework as claimed by NYT? Assume that sigma is 0.5. |
Algebraic Expression:
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42) Problem #PRAF7TJ "PRAF7TJ - 176367 - Z Test For 1 Prop..." |
Z Test For 1 Proportion A survey given in Boston Latin School showed that 123 students out of a sample of 400 students prefered Macs over PCs. Take the 99% confidence interval of this proportion. |
Multiple Choice:
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Hints: |
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z star = 2.576 n = 400 |
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43) Problem #PRAF7TZ "PRAF7TZ - 176381 - Z Test For 1 Prop..." |
Z Test For 1 Proportion Robert Akeson once said that the water in the BLS was not safe to drink due to a murky greenish contamination in the water. At that time, a random survey was given to 600 BLS student. 523 students agreed that the water was not safe to drink. Find the 99% confidence interval of students who agree that the water is not safe to drink. |
Multiple Choice:
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Hints: |
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z star = 2.576 n = 600 |
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44) Problem #PRAF7U3 "PRAF7U3 - 176414 - t test for a popu..." |
t test for a population mean (s is known - sigma is not knows) In a heated debate on SAT scores and college acceptances, Mr. Rogers states that most kids can't get a 2000 on the SATs. A random sample of 3000 BLS kids are surveyed, and found that the mean score was a 1800 on the SATs, a bit below the 2000 score that Mr. Rogers stated. Is this sample result good evidence that most kids can't get a 2000 on the SATs? Assume that is 100. Test significance at alpha level of 0.05. |
Multiple Choice:
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Hints: |
Ha = Most students can't get higher than 2000. |
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45) Problem #PRAF6M7 "PRAF6M7 - 175240 - A study claims th..." |
A)
A study claims that the average household in the United States has 3 computers. A sample of 500 households is surveyed and the sample mean is 4 computers. At the 5% significance level, can you claim that the number of computers in the average household in the united states is not 3? Assume that the standard deviation of all households is 1 computer. What kind of test statictic will you use? |
Multiple Choice:
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B)
Refer to the previous problem. What is the value of the z test statistic? Round to the nearest hundredth. |
Algebraic Expression:
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C)
Refer to the previous problem. Which is the best answer for the p-value of this problem? |
Multiple Choice:
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D)
What is your conclusion? |
Multiple Choice:
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46) Problem #PRAF76R "PRAF76R - 176714 - A study claims th..." |
A)
A study claims that the average dress size of women ages 18 to 35 is size 8. You survey 100 women ages 18 to 35 and find an average size 6 and a standard deviation of 1. Test the claim at a 0.05% significance level. What kind of test statictic will you use? |
Multiple Choice:
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B)
Refer to the previous problem. What is the value of the t test statistic? Round to the nearest hundredth. |
Algebraic Expression:
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C)
Refer to the previous problem. Which is the best answer for the p-value of this problem? |
Multiple Choice:
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D)
What is your conclusion? |
Multiple Choice:
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47) Problem #PRAF76T "PRAF76T - 176716 - A study claims th..." |
A)
A study claims that the average percent of high school students taking at least one AP class is 89.8%. You survey the 200 students in your school and find that 91% are taking at least one AP class. Test the claim at the 0.05% significance level. What kind of test statictic will you use? |
Multiple Choice:
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B)
Refer to the previous problem. What is the value of the z test statistic? Round to the nearest hundredth. |
Algebraic Expression:
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C)
Refer to the previous problem. What is the p-value of this problem? |
Algebraic Expression:
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D)
What is your conclusion? |
Multiple Choice:
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48) Problem #PRAF76V "PRAF76V - 176718 - A study claims th..." |
A)
A study claims that the average percent of high school seniors that will go onto a four year college is 61.4%. Of the 120 seniors in your high school, 73.4% will be attending a four year college in the fall. Test the claim at the 0.05% significance level. What kind of test statictic will you use? |
Multiple Choice:
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B)
Refer to the previous problem. What is the value of the z test statistic? Round to the nearest hundredth. |
Algebraic Expression:
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C)
Refer to the previous problem. What is the p-value of this problem? |
Algebraic Expression:
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D)
What is your conclusion? |
Multiple Choice:
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49) Problem #PRAF76X "PRAF76X - 176720 - The principal of ..." |
A)
The principal of a school is informed that the average score of her students on a school-wide exam last year was 83 with a standard deviation of 7. For this year's exam, she looks into the scores of a particular class of 30 students, and finds that x-bar=81.53. Based on this information, do this year's scores mark a significant divergence from those of previous years? |
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B)
For his senior thesis, a college student wants to do a project on the number of people who have ever been involved in at least one car accident during their lifetime. He interviewed 2417 people and found that 156 of them had been involved in a car accident. Based on this information, give a 95% confidence interval for the percent of the population that has ever been involved in at least one car accident. (Consider it an SRS of size 2417). |
Multiple Choice:
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C)
In the wake of recent events occurring in schools, a high school principal wants to know, in general, how many students have been subjected to bullying at least once during their four years of high school. She conducts a survey among 2368 high school students and finds that 1217 of them reported having been bullied. Is this strong evidence to support that more than half of high school students are bullied? |
Algebraic Expression:
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50) Problem #PRAF76M "PRAF76M - 176710 - Grendan Industrie..." |
A)
Grendan Industries found that the standard deviation was 15 points, but their specialists where captured before they could find the mean of the population. Grendan Industries wants to find an approximate value for the parameter of the customer assessment score on its products through statistical estimation for a population of customers. As a small upcoming industry, their current sample size is a mere 30 customers and from this sample they have found the mean (x bar) to be 81 with a standard deviation of 10. What is a 95% confidence interval for mean of the population of customers? Answer in (Lower Number,Higher Number) form. (Round to the Thousandths: 0.123) |
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B)
Now find the 95% confidence interval IF Grendan Industries did not have a value for the standard deviation of the population. Answer in (Lower Number, Higher Number) form. (Round to Thousandths place: 0.123) |
Algebraic Expression:
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51) Problem #PRAF76S "PRAF76S - 176715 - A new Tower Defen..." |
A new Tower Defense system has been tested 260 times and is able to eliminate all of the attacking enemies 65% of the time. What is the 98% confidence interval for the population proportion (True Elimination Rate). Answer in (Lower Number,Higher Number) Form. (Round to Thousandths place: 0.123) |
Algebraic Expression:
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52) Problem #PRAF76Y "PRAF76Y - 176721 - The Zephyr Corpor..." |
A)
The Zephyr Corporation has found through investigation that the standard deviation of a lamp base was 2.3cm, but they were unable to find the record containing the mean of the population. To estimate the parameter μ of the lamp bases, sample statistics of the population have been found with a sample size of 300 lamp bases with a mean (x bar) of 21cm with standard deviation of 3.7cm. Find the 90% confidence interval for the mean of the population. Answer in (Lower Number,Higher Number) form. (Round to thousandths place: 0.123) |
Algebraic Expression:
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B)
If the Zephyr Corporation did not know the standard deviation of the population, what is the new 90% confidence interval? Answer in (Lower Number,Higher Number) form. (Round to thousandths place: 0.123) |
Algebraic Expression:
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53) Problem #PRAF76Z "PRAF76Z - 176722 - Aorthena, a compa..." |
Aorthena, a company that produces sport bottles, has collected a sample of 800 sport bottles with a 92% rate of producing non-leaking sport bottles. What is the 99.9% confidence interval for the population proportion? Answer in (Lower Number,Higher Number) Form. (Round to Thousandths place: 0.123) |
Algebraic Expression:
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Hints: |
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54) Problem #PRAF763 "PRAF763 - 176724 - A peach farmer is..." |
A)
A peach farmer is trying to determine if his new fertilizer will cause the peaches to grow larger. The average weight of a peach is 6 ounces with a standard deviation (σ) of 4.1. From a sample of 25 peaches, the average weight came out to be 8.2 ounces. Is this sample evidence that the peaches grew larger? What is the z-value? Round to the nearest hundredth. |
Algebraic Expression:
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B)
What is the P-value? Round to the nearest thousandth. |
Algebraic Expression:
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C)
Conclusion (alpha=0.05)? |
Multiple Choice:
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55) Problem #PRAF764 "PRAF764 - 176725 - A study is being ..." |
A)
A study is being conducted on the memories of children. Studies have proven that children have a higher memory percentage than 74%. To test this, the children in the study played a memory card game where the cards were all mixed up and they had to match up the pairs. In this study of 46 children, the average was 82%. Does this study show any significance if alpha=0.01? What is z? Round to the nearest hundredth. |
Algebraic Expression:
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B)
What is the P-value? Round to the nearest hundredth. |
Algebraic Expression:
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C)
What is the conclusion of this study? |
Multiple Choice:
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56) Problem #PRAF768 "PRAF768 - 176729 - A potato chip com..." |
A)
A potato chip company sells bags of chips that claim to be 56 ounces. Our study group took a sample of 43 bags of chips. We found that the average weight of the bags is 52 ounces with a sample standard deviation of 3.5. Is this enough evidence to conclude that weight of the bags is less than 56 ounces? Find the t-value. Round to the nearest hundredth. |
Algebraic Expression:
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B)
If the confidence level is 99%, what is the result of the study? |
Algebraic Expression:
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57) Problem #PRAF765 "PRAF765 - 176726 - Nintendo is deter..." |
A)
Nintendo is determing the how long a fully charged battery on a Nintendo DS can last. The average of all batteries is 57 hours and the standard deviation of the population is 11.2. Nintendo took a sample of 100 Nintendo DSes and left them on until the battery went out. The average of the sample was 50. Is there evidence that the average life span doesn't equal 57 hours? What is the z-value? Round to the nearest hundredth. |
Algebraic Expression:
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B)
What is the P-value? |
Algebraic Expression:
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C)
What is the conclusion of the test if alpha-0.05? |
Multiple Choice:
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58) Problem #PRAF77A "PRAF77A - 176731 - An ornithologist ..." |
A)
An ornithologist is studying the size of blue jay eggs. The average size is 10 ounces. In a sample of 9 blue jay eggs, the average weight was 11 ounces and the standard deviation was 2.09. Is there evidence that the blue jay eggs are actually less than 10 ounces? What is the t-value? Round to the nearest hundredth. |
Algebraic Expression:
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B)
If the confidence level is 95%, what is the conclusion of the study? |
Algebraic Expression:
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59) Problem #PRAF73K "PRAF73K - 176616 - The sponsors of a..." |
A)
The sponsors of a city marathon are attempting to encourage more women to take part in the event. A sample of 70 runner is taken, of which 32 are women. The sponsors would like to be 90% certain that at least 40% of the participants are women. What is the null hypothesis and the alternative hypothesis for this problem? |
Multiple Choice:
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B)
Were the recruitment efforts of the sponsors successful? |
Multiple Choice:
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Hints: |
z = p-hat (the sample proportion) - (the hypothesized proportion) / the square root of {(the hypothesized proportion)(1- the hypothesized proportion)/ n} |
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60) Problem #PRAF77B "PRAF77B - 176732 - A professor..." |
A)
A professor wants to know if her introductory statistics class has a good grasp of basic math. Six students are chosen at random from the class and given a math proficiency test. The professor wants the class to be able to score at least 70 on the test. The six students get scores of 62, 92, 75, 68, 83, and 95. What type of inference test should be used in this case? |
Multiple Choice:
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Hints: |
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B)
A teacher wants to know if her introductory statistics class has a good grasp of basic math. Six students are chosen at random from the class and given a math proficiency test. The professor wants the class to be able to score at least 70 on the test. The six students get scores of 62, 92, 75, 68, 83, and 95. What is the sample mean for this problem? Round your answer to the nearest hundredth. |
Algebraic Expression:
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Hints: |
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C)
What is the standard deviation of the sample? Round your answer to the closest hundredth. |
Algebraic Expression:
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Hints: |
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D)
Can the professor be certain that the mean score for the class on the test would be at least 70? Assume that alpha = .10. |
Multiple Choice:
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Hints: |
Delta is equal to the population mean that the professor wishes to obtain; in this case, the professor hopes to obtain a mean of 70. Use the values you have previously calculated and plug them into the equation. |
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61) Problem #PRAF767 "PRAF767 - 176728 - The average amoun..." |
A)
The average amount a family pays in bills is $1800. Some believe the true mean is higher than that amount. A random sample of 40 families was taken and the sample mean was found to be $1950. If the standard deviation was $500, what is the Z score? (3 decimal places) |
Algebraic Expression:
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B)
If alpha is .05 should there be concerns that there is a significant difference in the cost? |
Multiple Choice:
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62) Problem #PRAF769 "PRAF769 - 176730 - Professor Profess..." |
A)
Professor Professorson wants to know if naughty children have have low IQ scores. Suppose the average IQ score is 102. Professor Professorson took a random sample of twenty naughty children. Their sample average was 110.5 and the standard deviation of the sample was 13.12. If alpha is .05 what is the t-value? |
Algebraic Expression:
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B)
What conclusion is drawn from the test with an alpha of .05? |
Multiple Choice:
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63) Problem #PRAF77C "PRAF77C - 176733 - A school district..." |
A)
A school district claims 80% of the students are satisfied with their teacher's performance. A newspaper takes a 100 random samples of students and only 73% said they were satisfied with the performance. With a .05 significance level what is the Z score? |
Algebraic Expression:
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B)
With an alpha of 0.05 do we fail to reject or reject the null hypothesis that the proportion is equal to .8? |
Multiple Choice:
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64) Problem #PRAF6MD "PRAF6MD - Population Mean" |
A)
The MBTA claims that the mean amount of time between two 39 buses is 5.5 minutes and the standard deviation is 3.2. An student from Boston Latin School who takes the bus everyday is skeptical and decides to keep a record of the time every afternoon at the Longwood stop 3:00 for 25 weekdays. She finds that the average time in this sample is x-bar = 7.3 minutes. Assume the standard deviation is also 2. H0: μ = 5.5 Ha: μ ≠ The average differs from 5.5 Calculate the statistic, round to the nearest hundredth. (Z-score) |
Multiple Choice:
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B)
Find the P-value. |
Exact Match (case sensitive):
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65) Problem #PRAF77F "PRAF77F - 176736 - Pop Mean (sigman unknown)" |
A)
The one-sample t statistic for testing
H0=0 HA>0 from a sample of n = 18 observations has the value of t = 1.93. What are the degrees of freedom? |
Algebraic Expression:
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B)
Give 2 critical values t* from Table C that bracket t. |
Multiple Choice:
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C)
Between what two values does the P-value of the test fall? |
Multiple Choice:
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66) Problem #PRAF6MF "PRAF6MF - 175217 - Population Mean (sigma unknown)" |
The chart above represents the number of wins the Red Sox have had from the years 2004 to 2010. Find a 95% confidence interval for the mean. Round to the nearest tenth. |
Multiple Choice:
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67) Problem #PRAF6ME "PRAF6ME - 1 Proportion" |
The BLS Survey Committee discovered that 93 students out of a the a sample of 826 consider math their favorite subject, which is p-hat=0.133. Find a 95% confidence interval of students who would say that math is their favorite subject. Round to the nearest thousandth. |
Multiple Choice:
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68) Problem #PRAF77D "PRAF77D - 1 Proportion2" |
The Boston Globe published a poll of 2,371 randomly selected men aged from 30 to 35. Of these men, 512 said that football was their favorite sport to watch. Give a 95% confidence interval for the proportion of all men in this age group would consider football their favorite sport to watch. Round to the nearest thousandth. |
Multiple Choice:
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69) Problem #PRAF7XT "PRAF7XT - Z Test for Pop. Mean" |
A)
What assumption can we make when we do a Z test for a population mean when the sigma is known? |
Multiple Choice:
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B)
A recent survey states that the average amount of sleep per night among adults is 7.5 hours with a standard deviation of .25 hours. But you conduct an SRS and find the mean to be 7.7 among a population of 30 adults. Use a Z test to determine whether the sample differs from the population. What is the Z score? Round to the hundredth. |
Algebraic Expression:
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Hints: |
σ/√n |
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70) Problem #PRAF78H "PRAF78H - Z test for one proportion" |
A)
What are the conditions for inference about a proportion? |
Multiple Choice:
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B)
If the null hypothesis is p ≠ p0... |
Multiple Choice:
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71) 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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72) Problem #PRAF78G "PRAF78G - 176768 - When you want to ..." |
A)
When you want to compare a mean of a sample to see whether or not that mean is significantly higher or lower than the population mean, you want to find the z-score of the sample first. Take for example that the national average of a test has the mean 100 with a standard deviation of 12. But when 55 students took the test at BLS, the mean was 96. You want to find out whether or not this was significantly lower than what was expected. To do this, you want to use the equation z = sample mean - mu / the standard error. The standard error = sigma / sqrt of n. In this example, find the z-score using the equation given above. |
Algebraic Expression:
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B)
Great! Now that you know the z-score, you can now find the p-value of -2.47 by going to the z-table. If we are testing with alpha = 0.05, can we safely conclude that the average for BLS students for this test is significantly lower than the national average? |
Multiple Choice:
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C)
Now we're going to look at testing the significance of proportions. Let's take the following example into account ... 10% of your clients say that they received poor service from your agency. After firing most of your employees and reworking your entire system on how you dealt with clients, 6 months later, 110 clients were sampled and it was reported that now 15% of them say they received poor service! Now the question is: Is there a statistically significant difference between the service your clients received 6 months ago and now? To approach this problem, you need to use the equation z = proportion 2 - proportion 1 / the standard error. In this equation, the standard error = sqrt of (p1)(q1)/n. Given this equation, what is the calcualted z-score? |
Algebraic Expression:
|
Hints: |
z = 0.15-0.10/0.029 ...given that the standard error = sqrt (0.10)(0.90)/110 |
D)
Now that you know the z-score, you can now calculate the p-value again by looking at a z-table. Using this information, can you safely assume that there is a statistically significance difference between the proportion of dissatisifed clients 6 months ago and now? (Assume we are testing at alpha = 0.05) |
Multiple Choice:
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E)
Next, we are going to look at the t-test for a population mean where the sample standard deviation is known, but actual sigma is not. This test is actually very simple. The equation we are dealing with is simply t = x-bar (sample mean) - mu (population mean) / (sample standard deviation/sqrt n). The one difference is that for t, we need to use the degrees of freedom equation is n - 1 and then look at the t-table. Take for example, the following example. Mr. Simeauno distributed a super hard statistics test to his AP class. He wanted to make sure that the average for the class would be at least a 70. Taking a sample of 6 students, the mean ended up being 79.19 with a sample standard deviation of 13.17. Using the equation above, what is the t-score and degrees of freedom? |
Multiple Choice:
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F)
Good. Now that we know the t-score, we can simply go to the t-table and find the t-score. Go to row 5 and look for the two values that contain the value 1.71 between them. Go up the table to find the what value the t-score lies between. Using the process described above, can we reject the null hypothesis, that Mr. Simeauno could assume the mean would be less than 70, or fail to reject, that Mr. Simeauno could assume that the mean would be greater than or equal to 70? (Assume that we are testing alpha = 0.05) |
Multiple Choice:
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73) Problem #PRAF78N "PRAF78N - 176773 - Now we're going t..." |
A)
Now we're going to look at testing the significance of proportions. Let's take the following example into account ... 10% of your clients say that they received poor service from your agency. After firing most of your employees and reworking your entire system on how you dealt with clients, 6 months later, 110 clients were sampled and it was reported that now 15% of them say they received poor service! Now the question is: Is there a statistically significant difference between the service your clients received 6 months ago and now? To approach this problem, you need to use the equation z = proportion 2 - proportion 1 / the standard error. In this equation, the standard error = sqrt of (p1)(q1)/n. Given this equation, what is the calcualted z-score? |
Algebraic Expression:
|
Hints: |
z = 0.15-0.10/0.029 ...given that the standard error = sqrt (0.10)(0.90)/110 |
B)
Now that you know the z-score, you can now calculate the p-value again by looking at a z-table. Using this information, can you safely assume that there is a statistically significance difference between the proportion of dissatisifed clients 6 months ago and now? (Assume we are testing at alpha = 0.05) |
Multiple Choice:
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74) Problem #PRAF78Q "PRAF78Q - 176775 - Next, we are goi..." |
A)
Next, we are going to look at the t-test for a population mean where the sample standard deviation is known, but actual sigma is not. This test is actually very simple. The equation we are dealing with is simply t = x-bar (sample mean) - mu (population mean) / (sample standard deviation/sqrt n). The one difference is that for t, we need to use the degrees of freedom equation is n - 1 and then look at the t-table. Take for example, the following example. Mr. Simeauno distributed a super hard statistics test to his AP class. He wanted to make sure that the average for the class would be at least a 70. Taking a sample of 6 students, the mean ended up being 79.19 with a sample standard deviation of 13.17. Using the equation above, what is the t-score and degrees of freedom? |
Multiple Choice:
|
B)
Good. Now that we know the t-score, we can simply go to the t-table and find the t-score. Go to row 5 and look for the two values that contain the value 1.71 between them. Go up the table to find the what value the t-score lies between. Using the process described above, can we reject the null hypothesis, that Mr. Simeauno could assume the mean would be less than 70, or fail to reject, that Mr. Simeauno could assume that the mean would be greater than or equal to 70? (Assume that we are testing alpha = 0.05) |
Multiple Choice:
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75) Problem #PRAF78J "PRAF78J - 176770 - The average perso..." |
The average person leaves the country to travel 15 times during their lifetime, with a standard deviation of 5 trips. A student believes that people actually take less trips than this. In a study conducted on 100 people, the mean number of trips taken out of the country was 18. What is z? |
Algebraic Expression:
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76) Problem #PRAF78K "PRAF78K - 176771 - What is the proba..." |
What is the probability that the student's prediction is true? |
Multiple Choice:
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77) Problem #PRAF78M "PRAF78M - 176772 - Florida believes ..." |
Florida believes that 70% of its high school graduates go to college. In a survey conducted on high school seniors, 600 out of the 1000 students said that they were going to college next year. What is z? |
Algebraic Expression:
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78) Problem #PRAF78P "PRAF78P - 176774 - Conduct a 90% con..." |
Conduct a 90% confidence level for these results. |
Multiple Choice:
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79) Problem #PRAF78R "PRAF78R - 176776 - There are suppose..." |
There are supposed to be 15 red M&M's in a large bag of M&M's. 10 bags were brought into a class and the students counted the number of red M&M's in each bag. Here are the results: 10, 12, 18, 13, 15, 9, 16, 17, 14, 11 What is the mean and standard deviation of this set of data? |
Multiple Choice:
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80) Problem #PRAF78U "PRAF78U - Population Mean (sigma unknown)" |
A)
A professor believes there are more absences among students on Monday than on other days of the week. The class has 50 students. The table below gives the number of students absent from class on Mondays and Fridays for a six-week period. Does this data provide evidence there are more absences of Monday? Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Monday 4 9 6 2 3 2 Friday 2 7 8 4 3 3 First, what is the t-value? |
Algebraic Expression:
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B)
What is the degrees of freedom? |
Algebraic Expression:
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C)
What is the conclusion? |
Multiple Choice:
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81) Problem #PRAF78V "PRAF78V - Test for 1 Proportion" |
A)
Suppose a blood test detects white blood cell malfunction in 85% of the people who have this disease. 175 people are known to have this malfunction in their white blood cell, but only 141 are detected to have this disease. Does this provide evidence that the screening test detects the disease at a rate other than 85% as claimed by the manufacturer? First, what is the z-value? |
Algebraic Expression:
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B)
What is the p-value? |
Algebraic Expression:
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C)
What is the conclusion? |
Multiple Choice:
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82) Problem #PRAF78Z "PRAF78Z - 176784 - Find the p value ..." |
A)
Find the p value given this problem. In a given high school data is being collected from all of the seniors about their score on a given english test. The highest score possible is 100 and the lowest is zero. H0: mu is equal to 85 HA: mu is not equal to 85 A SRS is taken of 100 students and the average comes out to be 87. With a standard deviation of 5, find a p value. |
Exact Match (case sensitive):
|
B)
If another SRS was taken and the average came out to be 83.5 what would the p value change too ? Round to the nearest thousandths. |
Exact Match (case sensitive):
|
83) Problem #PRAF782 "PRAF782 - 176785 - A study was done ..." |
A)
A study was done of how many college students eat fast food. In a representative sample of 150 colleges and 20,000 students, 8,000 students said they consume fast food. Considering this an SRS of 20,000 from the population of all college students, does this constitute strong evidence that more then 35% of all college students engaged in binge drinking? H0: p=.40 HA: p>.40 p-hat: (8000/20000)=.4 |
Exact Match (case sensitive):
|
B)
What assumptions must be made for the previous problem? |
Check All That Apply:
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84) Problem #PRAF784 "PRAF784 - 176787 - A company is test..." |
A)
A company is testing their fruit for loss of sweetness during transportation. Trained taste testers rate the sweetness before and after storage. Here are the sweetness losses found by 10 taste testers. .7, 1.2, 1.3, .6, 1.8,2, -1.4, -1, .4, -.7 H0: mu(difference)=0 HA: mu(difference)>0 Find the one-sample t test statistic Round to the nearest hundreths. |
Exact Match (case sensitive):
|
B)
Find the P value. |
Multiple Choice:
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85) Problem #PRAF788 "PRAF788 - 176791 - One statistician ..." |
One statistician claims that the average amount of a time a high school junior sleeps is 6 hours with a standard deviation of 1.5 hours. Another statistician doubts that it is 6 hours, so he takes a random sample of 20 juniors and found that the mean was 7 hours. Find the p-value. Round to the thousandth place |
Algebraic Expression:
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86) Problem #PRAF789 "PRAF789 - 176792 - A recent research..." |
A)
A recent researched showed that 85% of students have cheated on tests before. In and SRS of 250 students, 220 students claimed that they have cheated on tests, and you want to know whether the populations average is actually greater than 85%. Calculate the z statistic. Round to the hundredth place. |
Algebraic Expression:
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B)
What is the p-value? round to the hundredth place. |
Algebraic Expression:
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C) |
Multiple Choice:
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87) Problem #PRAF79A "PRAF79A - 176793 - In a game of Conn..." |
In a game of Connect Four, Sam won 67 out of 88 times. Construct a 95% confidence level to show Sam's probability of winning. |
Multiple Choice:
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88) Problem #PRAF79D "PRAF79D - 176796 - A math teacher ca..." |
A)
A math teacher calculates the average test score on the final. The test scores for 15 students are 65, 78, 92, 76, 87, 65, 88, 89, 98, 78, 77, 87, 88, 86, 93. She believes that the population mean for math finals should be 85. Calculate the t statistic. Round to the hundredth place. |
Algebraic Expression:
|
B)
If alpha is 0.05, what is the conclusion? |
Algebraic Expression:
|
89) Problem #PRAF786 "PRAF786 - 176789 - Z test for a popu..." |
Z test for a population mean (sigma is known) The Boston Globe reports that the average number of hours an American teen spends on Facebook is 4 hours. A group of 20 students were surveys and the average time spent on Facebook of this group is 2 hours. Is this good evidence that this sample differs from the average amount of time spent on Facebook as claimed by the Boston Globe? Assume that sigma is 1.2. |
Multiple Choice:
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90) Problem #PRAF79F "PRAF79F - 176798 - z test for 1 prop..." |
z test for 1 proportion 280 BLS seniors out of 300 BLS seniors believe that there should be no more work for seniors. 97% of the seniors in the United States feel the same way. Is there good evidence to show that the sample proporation is different from the population proportion? |
Multiple Choice:
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91) Problem #PRAF79J "PRAF79J - 176801 - z test for 1 prop..." |
z test for 1 proportion A report shows that 62% of children are allergic to peanut butter. A group of 80 kids were surveyed and 60% of them are allergic to peanut butter. Is there good evidence to show that the sample proporation is different from the population proportion? |
Multiple Choice:
|
92) Problem #PRAF79K "PRAF79K - 176802 - t test for a popu..." |
t test for a population mean (s is known - sigma is not known) 20 adults were surveyed on how much it cost to fill their tank up and the average is $32.60. In the Unitied States, it is found that the the average cost is $30. Find the p-value to see if the cost is different than as claimed. Asumme the s is $4.70. |
Multiple Choice:
|
93) Problem #PRAF5Y4 "PRAF5Y4 - 174617 - A chip company sa..." |
A chip company says that a bag of chips contains 5 oz of chips with a standard deviation of 0.04 oz You are very skeptical of the company and think that they are cheating you out of your money and giving less to you than you deserve and so you decide to test what they are saying, you test 10 bags of chips and come up with the following for the weights of the chips: 4.97 oz, 4.89 oz, 5.01 oz, 5 oz, 4.78 oz, 5 oz, 5.03 oz. 4.79 oz, 4.88 oz, and 5.03 oz. If alpha is 0.05, is the evidence you collected convincing? And state the p value. |
Algebraic Expression:
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94) Problem #PRAF5Y5 "PRAF5Y5 - 174618 - Check all of the ..." |
Check all of the conditions needed to conduct a proportion z-test. |
Check All That Apply:
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95) Problem #PRAF5Y6 "PRAF5Y6 - 174619 - Are all of the co..." |
Are all of the conditions met in the following situation. You toss a coin 7 times with the expected value of 0.5 for heads and 0.5 for tails. |
Multiple Choice:
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96) Problem #PRAF5Y7 "PRAF5Y7 - 174620 - You are thinking ..." |
A)
You are thinking about buying a store front to open up your new buisness and you are curious to know how many people walk by the store because you are curious about how much foot traffic will go by your store. The realtor tell you that on average there are about 100 people who walk by the store front an hour. You are skeptical and thinks that the number is less and that the realtor is lying to you to make you buy the store, so you decide to test it out. You test the number of people who walk by for 10 hours and here are the number of people you collected. 109, 100, 98, 87, 78, 111, 99, 95, 103, and 54. What is the p value? |
Multiple Choice:
|
B)
If alpha is 0.10, is the woman realtor telling you the truth or not? |
Multiple Choice:
|
97) Problem #PRAF8TC "PRAF8TC - 177322 - Problem #177322" |
Algebraic Expression: |
98) Problem #PRAF8TB "PRAF8TB - 177321 - A sample of 70 do..." |
A)
A sample of 70 doctors is taken and 30 of them are women. The employers want to be 90% certain that at least 35% of the participants are women. What is the z-value? |
Algebraic Expression:
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B)
What is the probability that the z-value is less than 1.38? Can you reject the null? |
Multiple Choice:
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An error occured while attempting to print problem 1
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100) Problem #PRAF8ZQ "PRAF8ZQ - 177519 - Why is t used ins..." |
Why is t used instead of z? |
Multiple Choice:
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101) Problem #PRAF79P "PRAF79P - 176805 - Find Z using the ..." |
Find Z using the following data from a sample of 25 people x-bar= 135 μ0 = 140 sigma= 5 |
Multiple Choice:
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102) Problem #PRAF79Q "PRAF79Q - 176806 - Find the Z value ..." |
Find the Z value for a this sample of 64 people with the following data: x-bar= 78 μ0= 67 sigma= 9 |
Multiple Choice:
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103) Problem #PRAF79R "PRAF79R - 176807 - What is the..." |
What is the p-value of H(a) : p ≠ p0? |
Multiple Choice:
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104) Problem #PRAF79S "PRAF79S - 176808 - If z* of a propor..." |
If z* of a proportion is equal to 2.576, What is the confidence interval? |
Multiple Choice:
|
105) Problem #PRAF6M6 "PRAF6M6 - 175239 - According t..." |
A)
According to the National Health Organization, seafood poses a major threat to pregnant women. A national survey of pregnant women found that 58% said that seafood made their moods fluctuate during pregnancy. A random sample of 100 pregnant women finds that 61 had mood swings. Is this good reason to accept the national claim? What is the value of the z test statistics? Round to the nearest hundredths. HINT: z = p-hat - p / [sqrt ((p*q)/ n)] |
Algebraic Expression:
|
B)
What was the p-value? |
Algebraic Expression:
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C)
What is the conclusion that can be drawn? |
Multiple Choice:
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106) Problem #PRAF6M8 "PRAF6M8 - 175241 - A recent study fr..." |
A)
A recent study from Harvard University finds that the mean of battery life is 95%. A freshman wanted to verify that study and so he conducted a study consisting of 39 batteries, and has a mean of -1.10, with a standard deviation of 5.99. What is the pvalue? HINT: tn-1 = xbar - mu / (sample std / sqrt n) |
Algebraic Expression:
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B) |
Algebraic Expression: |
C)
What is the p-value? |
Multiple Choice:
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D)
What is your conclusion? |
Multiple Choice:
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E) |
Algebraic Expression: |
107) Problem #PRAF9MR "PRAF9MR - 178109 - A recent study co..." |
A)
A recent study conducted by College Board found that the average biology test score for men is 97 points, with a standard deviation of 25. A local biology teacher in Minesota claims that the average test score for men is indeed less than 97 points. This woman surveyed 100 men and found the mean to be 92 points. What is the value of the z test statistics? Round to the nearest hundredths. HINT: z= (xbar - mu ) / (sigma / sqrt n) |
Algebraic Expression:
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B)
What is the p- value? |
Algebraic Expression:
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C)
What is the conclusion (assuming she was testing the claim at a 5% significant level interval)? |
Algebraic Expression:
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108) Problem #PRAF9MS "PRAF9MS - 178110 - According t..." |
A)
According to a recent study, having a child can increase your happiness. A national survey found that 58% said that their children made them happier in general. A random sample of 100 finds that 49 felt happier. Is this good reason to accept the national claim? What is the value of the z test statistics? Round to the nearest hundredths. HINT: z = p-hat - p / [sqrt ((p*q)/ n)] |
Algebraic Expression:
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B)
What was the p-value? |
Algebraic Expression:
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C)
What is the conclusion that can be drawn? |
Multiple Choice:
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109) Problem #PRAF9NF "PRAF9NF - z test for 1 proportion" |
A) |
Multiple Choice:
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Multiple Choice:
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110) Problem #PRAF9SH "PRAF9SH - t test for population mean" |
A)
Boston Latin School did yet another survey and asked 20 students how much they loved their school on a scale of 1-10. We asked them once at the end of sixie year, and again at the end of senior year. The table below is the rating after sixie year minus the rating after senior year. 3.0 2.8 0.1 0.0 2.9 5.5 4.0 2.0 3.5 3.5 5.1 9.0 10.0 1.1 0.0 6.1 3.2 9.9 8.9 2.3 Make a stemplot and determine whether or not the distribution is somewhat normal. |
Multiple Choice:
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B) |
Multiple Choice:
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111) Problem #PRAF9K5 "PRAF9K5 - Z-Test Population Mean" |
A)
State Street recently claimed that on average their employees type 55 wpm (words per minute). After surveying 20 State Street employees, it was found that their average typing speed was 51 wpm, with a standard deviation of 8 wpm. Is this sufficient evidence to prove that State Street employees do indeed have an average of 55 wpm? What is the z-score? Round the answer to the nearest hundredths. |
Algebraic Expression:
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B)
Based on your z-score, what is the p-value? Is the result significant at the 5% level? *Note: Ho: u = 55; Ha: u ≠ 55 |
Multiple Choice:
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112) Problem #PRAF9MG "PRAF9MG - Z- Test Proportion" |
A)
Mary spins a wheel, which is divided equally in half into a red section and a blue section. She spins the wheel 2459 times, and got the red section 1323 times. Mary claims the wheel is not fair. Is the evidence sufficient to prove her theory? What is the z-test statistic? Round to the nearest hundredths. |
Algebraic Expression:
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B)
Based on the z-test statistic, is the spinner fair? Why or why not? |
Multiple Choice:
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113) Problem #PRAF9MH "PRAF9MH - T-Test Population Mean" |
A)
Dunkin Donuts claims to use 2.5 teaspoons of sugar per regular medium cup of coffee. 10 food tasters went around to different Dunkin Donuts and found the differing teaspoons of sugar used: 2.5, 2.3, 2.4, 2.3, 2.1, 2.4, 2.1, 2.7, 2.9, 2.8 Are these data good evidence that the average amount of sugar used is not 2.5 teaspoons? Please first find the one-sample t test statistic. Round to the nearest hundredth. |
Algebraic Expression:
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B)
What is the resulting p-value? Can you reject the null hypothesis (the average is not 2.5 teaspoons of sugar)? |
Multiple Choice:
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114) Problem #PRAGAA3 "PRAGAA3 - 178770 - A health survey c..." |
A health survey came out saying that the mean blood pressure for women ages 60 to 70 is 130 and the standard deviation for this population is 10. The medical director looks at the charts of 70 women in this age group who went to a certain hospital in New York and finds that the mean blood pressure in this sample is 132. Is this evidence that the women at this hospital have a different mean blood pressure from the general population? alpha = .05 |
Multiple Choice:
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115) Problem #PRAGAA4 "PRAGAA4 - 178771 - The SAT website s..." |
The SAT website says that a score of 500 or higher on its math section reflects the skill needed to get through every day type of math. A random sample of 1,000 high school students had a mean score of 499. Is this sample good evidence that the mean for all students is less than 500? Assume the standard deviation for the population is 15 and alpha = .05. |
Multiple Choice:
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116) Problem #PRAGAA6 "PRAGAA6 - 178773 - A coin that is ba..." |
A coin that is balanced should land on heads half the time in the long run. A student tossed a coin 4,000 times. He got 2,050 heads. Is this evidence that the coin was not balanced? alpha = .05 |
Multiple Choice:
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117) Problem #PRAGAA7 "PRAGAA7 - 178774 - An alcohol study ..." |
An alcohol study researched high school students. Of a sample of 20,000 students, 5,000 students said that they use alcohol. Is this strong evidence that more than 20% of all high school students drink? alpha = .05 |
Multiple Choice:
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118) Problem #PRAGAA8 "PRAGAA8 - 178775 - Researches want t..." |
Researches want to know if listening to classical music enhances test scores. The 10 differences (test score with music - test score without music) give x-bar=2 and s=5. Is there convincing evidence that listening to classical music enhances test scores? alpha = .05 |
Multiple Choice:
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119) Problem #PRAF6VR "PRAF6VR - 175474 - The Probability o..." |
A)
The Probability of doing work in stats class is 90%. In a test of this on one class with 25 students, the Po was found to be 78%. Whats the z-score? Round to the hundreths |
Algebraic Expression:
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B)
Find the P-value. Was this test significant at a .05 level? |
Multiple Choice:
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120) Problem #PRAF6VJ "PRAF6VJ - 175468 - 20% of a sur..." |
A)
20% of a survey of 1000 people had AIDS. The standard deviation was 2%. In a sample of this survey with only the men, 37% of them had AIDS. There were 400 men. Find the z-score for this. |
Algebraic Expression:
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B)
Is this a significant difference? |
Algebraic Expression:
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121) Problem #PRAF6VE "PRAF6VE - 175464 - THe mean score of..." |
A)
THe mean score of every student who took the stats test is 66%. THe standard deviation is 5. The mean score of just one class was 71. Whats the z-score? Write the answer as a percent |
Algebraic Expression:
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B)
In another class the mean score was a 60. Find the z-score. At a significance level of .05, is this score within the normal range? |
Multiple Choice:
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