Question 1

When testing  the observed value of the z-score was found to be −2.15.Then,the p-value for this test would be

Accepted Answer

A) .0158 
B) .0316 
C) .9842 
D) .9684

Question 2

Speed Limits Violation
 Do out-of-state motorists violate the speed limit more frequently than in-state motorists? This vital question was addressed by the highway patrol in a large eastern state.A random sample of the speeds of 2,500 randomly selected cars was categorized according to whether the car was registered in the state or in some other state and whether or not the car was violating the speed limit.The data follow.  ​ ​
-{Speed Limits Violation Narrative} Estimate with 95% confidence the difference in population proportions.

Accepted Answer

The answer of Speed Limits Violation
 Do out-of-state motorists violate...

Question 3

When the necessary conditions are met,a two-tail test is being conducted at α = .05 to test  .The two sample variances are  and  ,and the sample sizes are n1 = 16and n2 = 25.The calculated value of the test statistic will be F = 0.33.

Accepted Answer

A) True 
 B)False

Question 4

____________________ samples are those for which the selection process for one is not related to the selection process for the other.

Accepted Answer

The answer of ____________________ samples are those for which the...

Question 5

The pooled proportion estimate is used when the null hypothesis states that the two population proportions differ by some non-zero number.

Accepted Answer

A) True 
 B)False

Question 6

When the sample sizes are equal,the pooled variance of the two samples is the weighted average of the two sample variances.

Accepted Answer

A) True 
 B)False

Question 7

Suppose we randomly selected 250 people,and on the basis of their responses to a survey we assigned them to one of two groups: high-risk group and low-risk group.We then recorded the blood pressure for the members of each group.Such data are called:

Accepted Answer

A) observational. 
B) experimental. 
C) matched. 
D) None of these choices.

Question 8

A required condition for using the normal approximation to the binomial in testing the difference between two population proportions is that n1p1 ≥ 30 and n2p2 ≥ 30.

Accepted Answer

A) True 
 B)False

Question 9

Profit Margin 
An investor is considering two types of investment.She is quite satisfied that the expected profit margin on Investment 1 is higher than the expected profit margin on Investment 2.However,she is quite concerned that the risk associated with Investment 1 is higher than that of Investment 2.To help make her decision,she randomly selects seven monthly profit margins on investment 1 and ten monthly profit margins on investment 2.She finds that the sample variances of Investments 1 and 2 are 225 and 118,respectively. ​ ​
-{Profit Margin Narrative} Briefly describe what the interval estimate tells you.

Accepted Answer

The answer of  Profit Margin 
An investor is considering...

Question 10

In testing the difference between two population means for which the population variances are unknown and not assumed to be equal,two independent samples are drawn from the populations.Which of the following tests is appropriate?

Accepted Answer

A) z-test 
B) pooled-variances t-test 
C) unequal variances t-test 
D) None of these choices.

Question 11

The variance of  .

Accepted Answer

A) True 
 B)False

Question 12

Mass Production Line
 A quality control examiner keeps a tally sheet of the number of acceptable and unacceptable products that come off two different production lines.The completed sheet is shown below.  ​ ​
-{Mass Production Line Narrative} Can the inspector infer at the 5% significance level that production line 1 is doing a better job than production line 2?

Accepted Answer

The answer of  Mass Production Line
 A quality control...

Question 13

Mass Production Line
 A quality control examiner keeps a tally sheet of the number of acceptable and unacceptable products that come off two different production lines.The completed sheet is shown below.  ​ ​
-{Mass Production Line Narrative} Estimate with 95% confidence the difference in population proportions.

Accepted Answer

The answer of  Mass Production Line
 A quality control...

Question 14

We use a t-test to determine whether two population variances are equal.

Accepted Answer

A) True 
 B)False

Question 15

The sampling distribution of the ratio of two sample variances  is said to be F-distributed provided that:

Accepted Answer

A) the samples are independent from any distributions. 
B) the populations are normal with equal variances. 
C) the samples are matched and their sizes are large. 
D) the samples are independently drawn from two normal populations.

Question 16

Headache Medicine
 A researcher wants to see if/how men and women differ in their reaction to a headache medicine with respect to drowsiness.In testing the hypotheses  .the following statistics were obtained: nS1U1B11S1U1B0 = 400,xS1U1B11S1U1B0 = 208,nS1U1B12S1U1B0 = 250,and xS1U1B12S1U1B0 = 115,where xS1U1B11S1U1B0 and xS1U1B12S1U1B0 represent the number of patients in the two samples (men vs.women)who reported to have drowsiness as a result of taking headache medicine. ​ ​
-{Headache Medicine Narrative} What conclusion can we draw at the 10% significance level?

Accepted Answer

The answer of Headache Medicine
 A researcher wants to see...

Question 17

Motorcycle insurance appraisers examine motorcycles that have been involved in accidental collisions to assess the cost of repairs.An insurance executive is concerned that different appraisers produce significantly different assessments.In an experiment 10 motorcycles that have recently been involved in accidents were shown to two appraisers.Each assessed the estimated repair costs.These results are shown below.Can the executive conclude at the 5% significance level that the appraisers differ in their assessments?

Accepted Answer

The answer of Motorcycle insurance appraisers examine motorcycles that have...

Question 18

A political analyst in Hawaii surveys a random sample of registered Democrats and compares the results with those obtained from a random sample of registered Republicans.This would be an example of:

Accepted Answer

A) independent samples. 
B) dependent samples. 
C) independent samples only if the sample sizes are equal. 
D) dependent samples only if the sample sizes are equal.

Question 19

The sampling distribution of  is normal if the sampled populations are normal,and approximately normal if the populations are nonnormal and the sample sizes n1 and n2 are large.

Accepted Answer

A) True 
 B)False

Question 20

The t-test for the difference between the means of two independent populations assumes that the respective:

Accepted Answer

A) sample sizes are equal. 
B) populations are normal. 
C) means are equal. 
D) All of these choices are true.

Exam 13: Inference About Comparing Two Populations

When testing the observed value of the z-score was found to be −2.15.Then,the p-value for this test would be

When the necessary conditions are met,a two-tail test is being conducted at α = .05 to test .The two sample variances are and ,and the sample sizes are n₁ = 16and n₂ = 25.The calculated value of the test statistic will be F = 0.33.

____________________ samples are those for which the selection process for one is not related to the selection process for the other.

The pooled proportion estimate is used when the null hypothesis states that the two population proportions differ by some non-zero number.

When the sample sizes are equal,the pooled variance of the two samples is the weighted average of the two sample variances.

Suppose we randomly selected 250 people,and on the basis of their responses to a survey we assigned them to one of two groups: high-risk group and low-risk group.We then recorded the blood pressure for the members of each group.Such data are called:

A required condition for using the normal approximation to the binomial in testing the difference between two population proportions is that n₁p₁ ≥ 30 and n₂p₂ ≥ 30.

In testing the difference between two population means for which the population variances are unknown and not assumed to be equal,two independent samples are drawn from the populations.Which of the following tests is appropriate?

The variance of .

We use a t-test to determine whether two population variances are equal.

The sampling distribution of the ratio of two sample variances is said to be F-distributed provided that:

A political analyst in Hawaii surveys a random sample of registered Democrats and compares the results with those obtained from a random sample of registered Republicans.This would be an example of:

The sampling distribution of is normal if the sampled populations are normal,and approximately normal if the populations are nonnormal and the sample sizes n₁ and n₂ are large.

The t-test for the difference between the means of two independent populations assumes that the respective: