N/A — Exam Answers

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The proportion of all US adults who eat popcorn when they go to the movie theater is p is equal to 0 point 8 7 A random sample of 20 US adults was selected and asked if they eat popcorn when they go to the movie theater. Which of the following is the shape of the sampling distribution of hat p ?

A
Because n times 1 minus p minus 20 times 1 minus 0 point 8 7 minus 2 point 6 is less than 10 , the sampling distribution of hat p is not approximately Normal. Because p is equal to 0 point 8 7 is closer to 1 than 0 , the sampling distribution of hat p is skewed to the right.
B
The sampling distribution of hat p is approximately Normal because .
C
Because n times 1 minus p minus 20 times 1 minus 0 point 8 7 minus 2 point 6 is less than 10 , the sampling distribution of hat p is not approximately Normal. Because p is equal to 0 point 8 7 is closer to 1 than 0 , the sampling distribution of hat p is skewed to the left.
D
Because n times 1 minus p minus 20 times 1 minus 0 point 8 7 minus 2 point 6 is less than 10 , the sampling distribution of hat p is not approximately Normal. The sampling distribution of hat p is skewed right and centered at 0 point 8 7 .
23
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A teacher has a large container of blue, red, and green beads. She reports to the students that the proportion of blue beads in the container is 0 point 3 0 The students feel the proportion of blue beads is lower than 0 point 3 0 A student randomly selects 60 beads and finds that 12 of the beads are blue. The cap p -value for the test of the hypotheses, ratio of cap h sub 0 to p is equal to 0 point 3 0 and ratio of cap h sub A to p is less than 0 point 3 0 , is 0 point 0 4 5 What is the correct interpretation of this value?

A
There is a 4 point 5 percent chance the proportion of blue beads in the container is 0 point 3 .
B
Assuming the true proportion of blue beads in the container is less than 0 point 3 0 , there is a 4 point 5 percent probability that the sample proportion would be 0 point 2 0 or less by chance alone.
C
Assuming the true proportion of blue beads in the container is 0 point 3 0 , there is a 4 point 5 percent probability that the sample proportion would be 0 point 2 0 or less by chance alone.
D
Assuming the true proportion of blue beads in the container is 0 point 3 0 , there is a 4 point 5 percent probability that the null hypothesis is true.
24

At a large company retreat, management orders subs for lunch. They hypothesize that 50 percent of the attendees will choose a turkey sub, 40 percent will choose a ham sub, and 10 percent will choose a vegetarian sub. Before placing the order, they select a random sample of 50 attendees and determine the type of sub they prefer. The management would like to know if there is convincing evidence that the distribution of sub preference differs from 50 percent turkey, 40 percent ham, and 10 percent vegetarian. What are the appropriate hypotheses?

A
cap h sub 0 : p sub turkey is equal to 25 , p sub ham is equal to 20 , p sub vegetarian is equal to 5 cap h sub A : Not all of the p sub i 's are as stated.
B
cap h sub 0 : p sub turkey is equal to 0 point 5 , p sub ham is equal to 0 point 4 , p sub vegetarian is equal to 0 point 1 cap h sub A : Not all of the p sub i 's are as stated.
C
cap h sub 0 : Not all of the p sub i 's are as stated. cap h sub A : p sub turkey is equal to 25 , p sub ham is equal to 20 , p sub vegetarian is equal to 5
D
cap h sub 0 : Not all of the p sub i 's are as stated. cap h sub A : p sub turkey is equal to 0 point 5 , p sub ham is equal to 0 point 4 , p sub vegetarian is equal to 0 point 1
25

A statistics class weighed 20 bags of grapes purchased from the store. The bags are advertised to contain 16 ounces, on average. The class calculated the 90 percent confidence interval for the true mean weight of bags of grapes from this store to be open paren 15 point 8 7 5 comma 16 point 5 9 5 close paren ounces. What is the sample mean weight of grapes, and what is the margin of error?

A
The sample mean weight is 15 point 8 7 5 ounces, and the margin of error is 16 point 5 9 5 ounces.
B
The sample mean weight is 16 point 2 3 5 ounces, and the margin of error is 0 point 3 6 0 ounces.
C
The sample mean weight is 16 ounces, and the margin of error is 0 point 7 2 0 ounces.
D
The sample mean weight is 16 point 2 3 5 ounces, and the margin of error is 0 point 7 2 0 ounces.
27

A 95 percent confidence interval for the true proportion of teenagers who have been to a professional sporting event is open paren 0 point 2 8 9 comma 0 point 4 1 6 close paren Is it reasonable to believe that more than 25 percent of teenagers have been to a professional sporting event?

A
No, because the center of the interval is 0 point 3 5 2 5 , which is not statistically greater than 0 point 2 5 .
B
Yes, because the entire interval is greater than 0 point 2 5 .
C
No, because there are values in the interval greater than 0 point 3 5 2 5 .
D
Yes, because 0 point 3 5 2 5 is in the interval.
28

The agent tests ratio of cap h sub 0 to mu sub 1 minus mu sub 2 is equal to 0 , ratio of cap h sub A to mu sub 1 minus mu sub 2 is less than 0 , where mu sub 1 is equal to the true mean selling price of all comparable empty homes and mu sub 2 is equal to the true mean selling price of all comparable staged homes. The conditions for inference are met. What are the values of the test statistic and cap p -value for a t - test about a difference in means? Use the t -table.

A
t is equal to the fraction with numerator 150 comma 000 minus 175 comma 000 and denominator square root of the fraction with numerator 22 comma 000 squared and denominator 5 plus the fraction with numerator 35 comma 000 squared and denominator 5 end root . The cap p -value is between 0 point 1 0 and 0 point 1 5 .
B
t is equal to the fraction with numerator 150 comma 000 minus 175 comma 000 and denominator square root of the fraction with numerator 22 comma 000 squared and denominator 5 plus the fraction with numerator 35 comma 000 squared and denominator 5 end root . The cap p -value is between 0 point 2 0 and 0 point 3 0 .
C
t is equal to the fraction with numerator 150 comma 000 minus 175 comma 000 and denominator square root of the fraction with numerator 22 comma 000 squared and denominator 5 minus the fraction with numerator 35 comma 000 squared and denominator 5 end root . The cap p -value is between 0 point 1 0 and 0 point 1 5 .
D
t is equal to the fraction with numerator 150 comma 000 minus 175 comma 000 and denominator square root of the fraction with numerator 22 comma 000 squared and denominator 5 minus the fraction with numerator 35 comma 000 squared and denominator 5 end root . The cap p -value is between 0 point 2 0 and 0 point 3 0 .
30

The mean of the differences is 193 points, and the standard deviation of the differences is 62 point 7 3 points. The conditions for inference are met. A 98 percent confidence interval for the mean difference (after – before) in score is 137 point 0 4 points to 248 point 9 6 points. What is the correct interpretation of this interval?

A
98 percent of students in this sample increased their score, on average, by 137 point 0 4 to 248 point 9 6 points.
B
98 percent of students who take this course will increase their score, on average, by 137 point 0 4 to 248 point 9 6 points.
C
The school can be 98 percent confident that the students in the sample increased their SAT score, on average, by 137 point 0 4 to 248 point 9 6 points.
D
The school can be 98 percent confident that students who take this course increase their SAT score, on average, by 137 point 0 4 to 248 point 9 6 points.
31

The chi-square test statistic is chi squared is equal to 12 point 7 1 and the cap p -value is between 0 point 0 0 1 and 0 point 0 0 2 What conclusion should the public relations department make? Use alpha is equal to 0 point 0 5

A
Fail to reject H . There is convincing evidence that the distribution of customer opinion is equally distributed across the three options.
B
Fail to reject H . There is convincing evidence that the distribution of customer opinion is not equally distributed across the three options.
C
Reject H . There is convincing evidence that the distribution of customer opinion is equally distributed across the three options.
D
Reject H . There is convincing evidence that the distribution of customer opinion is not equally distributed across the three options.
32

Which of the following is the correct interpretation of cap p times open paren cap x is less than or equal to 3 close paren ?

A
The probability that the number of free throws made out of 8 is at least 3 .
B
The probability that the number of free throws made out of 8 is higher than 3 .
C
The probability that the number of free throws made out of 8 is at most 3 .
D
The probability that the number of free throws made out of 8 is lower than 3 .

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