Question 1

When testing the difference between two population proportions using large independent random samples,the __________ test statistic is used.

Accepted Answer

A)  z 
B)  t 
C)  F 
D)  chi-square 
E)  None of the other choices is correct.

Question 2

The exact shape of the curve of the F distribution depends on two parameters,df1 and df2.

Accepted Answer

A) True 
 B)False

Question 3

If we are testing the hypothesis about the mean of a population of paired differences with samples of n1 = 8,n2 = 8,the degrees of freedom for the t statistic is ____.

Accepted Answer

A)  16 
B)  7 
C)  14 
D)  9

Question 4

In which of the following tests is the variable of interest the difference between the values of the observations from the two samples,rather than the actual observations themselves?

Accepted Answer

A)  a test of hypothesis about the mean of a population of paired differences selected from two related samples 
B)  a test of hypothesis about the difference between the means of two normally distributed populations using independent samples 
C)  a test of hypothesis about the difference between two population proportions,using large independent random samples 
D)  a test of hypothesis about the difference between the variances of two normally distributed populations using independent samples

Question 5

In testing the difference between the means of two normally distributed populations using independent random samples,the alternative hypothesis always indicates no differences between the two specified means.

Accepted Answer

A) True 
 B)False

Question 6

If we are testing the hypothesis about the mean of a population of paired differences with samples of n1 = 10,n2 = 10,the degrees of freedom for the t statistic is ____.

Accepted Answer

A)  19 
B)  18 
C)  9 
D)  8 
E)  10

Question 7

A new company is in the process of evaluating its customer service.The company offers two types of sales: (1)Internet sales and (2)store sales.The marketing research manager believes that the Internet sales are more than 10 percent higher than store sales.The null hypothesis would be

Accepted Answer

A)  PInternet − Pstore > .10. 
B)  PInternet − Pstore Internet − Pstore ³ .10. 
D)  PInternet − Pstore £ .10. 
E)  PInternet − Pstore = .10.

Question 8

When we test H₀: p₁ − p₂ £ .01,H_A: p₁ − p₂ > .01,at α = .05,where ₁ = .08, ₂ = .035,n₁ = 200,and n₂ = 400,what is the standard deviation used to calculate the test statistic?

Accepted Answer

The answer of When we test H₀: p₁ − p₂...

Question 9

In order to test the effectiveness of a drug called XZR designed to reduce cholesterol levels,the cholesterol levels of 9 heart patients are measured before they are given the drug.The same 9 patients use XZR for two continuous months.After two months of continuous use,the cholesterol levels are measured again.The comparison of cholesterol levels before versus after administering the drug is an example of testing the difference between

Accepted Answer

A)  two means from independent populations. 
B)  two population variances from independent populations. 
C)  two population proportions. 
D)  matched pairs from two dependent populations.

Question 10

Given the following information about a hypothesis test of the difference between two means based on independent random samples,which one of the following is the correct rejection region at a significance level of .05? HA: μA > μB,
= 12, 
= 9,s1 = 4,s2 = 2,n1 = 13,n2 = 10.

Accepted Answer

A)  Reject H0 if t > 1.96. 
B)  Reject H0 if t > 1.645. 
C)  Reject H0 if t > 1.721. 
D)  Reject H0 if t > 2.08. 
E)  Reject H0 if t > 1.782.

Question 11

Find a 95 percent confidence interval for μ₁ − μ₂,where n₁ = 9,n₂ = 6, = 64, = 59,s₁² = 6,and s₂² = 3.(Assume equal population variances. )

Accepted Answer

The answer of Find a 95 percent confidence interval for...

Question 12

In testing the difference between two means from two normally distributed independent populations,the distribution of the difference in sample means will be

Accepted Answer

A)  normally distributed only if sample sizes are equal. 
B)  normally distributed only if both population standard deviations are known. 
C)  normally distributed. 
D)  normally distributed if both sample sizes are very large. 
E)  normally distributed only if both population variances are equal.

Question 13

In testing the difference between the means of two independent populations,if neither population is normally distributed,then the sampling distribution of the difference in means will be approximately normal,provided that the sum of the sample sizes obtained from the two populations is at least 30.

Accepted Answer

A) True 
 B)False

Question 14

When testing the difference between two proportions selected from populations with large independent samples,the z test statistic is used.

Accepted Answer

A) True 
 B)False

Question 15

If the limits of the confidence interval of the difference between the means of two normally distributed populations were 8.5 and 11.5 at the 95 percent confidence level,then we can conclude that we are 95 percent certain that there is a significant difference between the two population means.

Accepted Answer

A) True 
 B)False

Question 16

When we are testing a hypothesis about the difference in two population proportions based on large independent samples,we compute a combined (pooled)proportion from the two samples if we assume that there is no difference between the two proportions in our null hypothesis.

Accepted Answer

A) True 
 B)False

Question 17

There are two types of machines,called type A and type B.Both type A and type B can be used to produce a certain product.The production manager wants to compare efficiency of the two machines.He assigns each of the 15 workers to both types of machines to compare their hourly production rate.In other words,each worker operates machine A and machine B for one hour each.These two samples are independent.
This is a paired sample because both machines have the same operators.

Accepted Answer

A) True 
 B)False

Question 18

In order to test the effectiveness of a drug called XZR designed to reduce cholesterol levels,the cholesterol levels of 9 heart patients are measured before they are given the drug.The same 9 patients use XZR for two continuous months.After two months of continuous use,the cholesterol levels are measured again.The comparison of cholesterol levels before versus after the administration of the drug is an example of testing the difference between two ____________.

Accepted Answer

A)  samples of equal variances 
B)  independent samples 
C)  paired samples 
D)  samples of unequal variances

Question 19

Parameters of the F distribution include

Accepted Answer

A)  n1. 
B)  degrees of freedom for the numerator and the denominator. 
C)  n2. 
D)  n1 and n2. 
E)  None of the other choices is correct.

Question 20

When we test H₀: μ₁ − μ₂ £ 0,H_A: μ₁ − μ₂ > 0, = 15.4, = 14.5,s₁ = 2,s₂ = 2.28,n₁ = 35,and n₂ = 18 at α = .01,can we reject the null hypothesis? (Assume unequal variances. )

Accepted Answer

The answer of When we test H₀: μ₁ − μ₂...

Exam 10: Statistical Inferences for Means and Proportions

When testing the difference between two population proportions using large independent random samples,the __________ test statistic is used.

The exact shape of the curve of the F distribution depends on two parameters,df₁ and df₂.

If we are testing the hypothesis about the mean of a population of paired differences with samples of n₁ = 8,n₂ = 8,the degrees of freedom for the t statistic is ____.

In which of the following tests is the variable of interest the difference between the values of the observations from the two samples,rather than the actual observations themselves?

In testing the difference between the means of two normally distributed populations using independent random samples,the alternative hypothesis always indicates no differences between the two specified means.

If we are testing the hypothesis about the mean of a population of paired differences with samples of n₁ = 10,n₂ = 10,the degrees of freedom for the t statistic is ____.

A new company is in the process of evaluating its customer service.The company offers two types of sales: (1) Internet sales and (2) store sales.The marketing research manager believes that the Internet sales are more than 10 percent higher than store sales.The null hypothesis would be

When we test H₀: p₁ − p₂ £ .01,H_A: p₁ − p₂ > .01,at α = .05,where ₁ = .08, 11ec8fe3_f0fe_0507_bdf7_b1edfdb0dc11_TB2569_11₂ = .035,n₁ = 200,and n₂ = 400,what is the standard deviation used to calculate the test statistic?

Given the following information about a hypothesis test of the difference between two means based on independent random samples,which one of the following is the correct rejection region at a significance level of .05? H_A: μ_A > μ_B, = 12, = 9,s₁ = 4,s₂ = 2,n₁ = 13,n₂ = 10.

Find a 95 percent confidence interval for μ₁ − μ₂,where n₁ = 9,n₂ = 6, = 64, = 59,s₁² = 6,and s₂² = 3.(Assume equal population variances. )

In testing the difference between two means from two normally distributed independent populations,the distribution of the difference in sample means will be

In testing the difference between the means of two independent populations,if neither population is normally distributed,then the sampling distribution of the difference in means will be approximately normal,provided that the sum of the sample sizes obtained from the two populations is at least 30.

When testing the difference between two proportions selected from populations with large independent samples,the z test statistic is used.

If the limits of the confidence interval of the difference between the means of two normally distributed populations were 8.5 and 11.5 at the 95 percent confidence level,then we can conclude that we are 95 percent certain that there is a significant difference between the two population means.

When we are testing a hypothesis about the difference in two population proportions based on large independent samples,we compute a combined (pooled)proportion from the two samples if we assume that there is no difference between the two proportions in our null hypothesis.

Parameters of the F distribution include

When we test H₀: μ₁ − μ₂ £ 0,H_A: μ₁ − μ₂ > 0, = 15.4, = 14.5,s₁ = 2,s₂ = 2.28,n₁ = 35,and n₂ = 18 at α = .01,can we reject the null hypothesis? (Assume unequal variances. )

Exam 10: Statistical Inferences for Means and Proportions

When testing the difference between two population proportions using large independent random samples,the __________ test statistic is used.

The exact shape of the curve of the F distribution depends on two parameters,df1 and df2.

If we are testing the hypothesis about the mean of a population of paired differences with samples of n1 = 8,n2 = 8,the degrees of freedom for the t statistic is ____.

In which of the following tests is the variable of interest the difference between the values of the observations from the two samples,rather than the actual observations themselves?

In testing the difference between the means of two normally distributed populations using independent random samples,the alternative hypothesis always indicates no differences between the two specified means.

If we are testing the hypothesis about the mean of a population of paired differences with samples of n1 = 10,n2 = 10,the degrees of freedom for the t statistic is ____.

A new company is in the process of evaluating its customer service.The company offers two types of sales: (1) Internet sales and (2) store sales.The marketing research manager believes that the Internet sales are more than 10 percent higher than store sales.The null hypothesis would be

When we test H0: p1 − p2 £ .01,HA: p1 − p2 > .01,at α = .05,where 1 = .08, 11ec8fe3_f0fe_0507_bdf7_b1edfdb0dc11_TB2569_112 = .035,n1 = 200,and n2 = 400,what is the standard deviation used to calculate the test statistic?

Given the following information about a hypothesis test of the difference between two means based on independent random samples,which one of the following is the correct rejection region at a significance level of .05? HA: μA > μB, = 12, = 9,s1 = 4,s2 = 2,n1 = 13,n2 = 10.

Find a 95 percent confidence interval for μ1 − μ2,where n1 = 9,n2 = 6, = 64, = 59,s12 = 6,and s22 = 3.(Assume equal population variances. )

In testing the difference between two means from two normally distributed independent populations,the distribution of the difference in sample means will be

In testing the difference between the means of two independent populations,if neither population is normally distributed,then the sampling distribution of the difference in means will be approximately normal,provided that the sum of the sample sizes obtained from the two populations is at least 30.

When testing the difference between two proportions selected from populations with large independent samples,the z test statistic is used.

If the limits of the confidence interval of the difference between the means of two normally distributed populations were 8.5 and 11.5 at the 95 percent confidence level,then we can conclude that we are 95 percent certain that there is a significant difference between the two population means.

When we are testing a hypothesis about the difference in two population proportions based on large independent samples,we compute a combined (pooled)proportion from the two samples if we assume that there is no difference between the two proportions in our null hypothesis.

Parameters of the F distribution include

When we test H0: μ1 − μ2 £ 0,HA: μ1 − μ2 > 0, = 15.4, = 14.5,s1 = 2,s2 = 2.28,n1 = 35,and n2 = 18 at α = .01,can we reject the null hypothesis? (Assume unequal variances. )

The exact shape of the curve of the F distribution depends on two parameters,df₁ and df₂.

If we are testing the hypothesis about the mean of a population of paired differences with samples of n₁ = 8,n₂ = 8,the degrees of freedom for the t statistic is ____.

If we are testing the hypothesis about the mean of a population of paired differences with samples of n₁ = 10,n₂ = 10,the degrees of freedom for the t statistic is ____.

When we test H₀: p₁ − p₂ £ .01,H_A: p₁ − p₂ > .01,at α = .05,where ₁ = .08, 11ec8fe3_f0fe_0507_bdf7_b1edfdb0dc11_TB2569_11₂ = .035,n₁ = 200,and n₂ = 400,what is the standard deviation used to calculate the test statistic?

Given the following information about a hypothesis test of the difference between two means based on independent random samples,which one of the following is the correct rejection region at a significance level of .05? H_A: μ_A > μ_B, = 12, = 9,s₁ = 4,s₂ = 2,n₁ = 13,n₂ = 10.

Find a 95 percent confidence interval for μ₁ − μ₂,where n₁ = 9,n₂ = 6, = 64, = 59,s₁² = 6,and s₂² = 3.(Assume equal population variances. )

When we test H₀: μ₁ − μ₂ £ 0,H_A: μ₁ − μ₂ > 0, = 15.4, = 14.5,s₁ = 2,s₂ = 2.28,n₁ = 35,and n₂ = 18 at α = .01,can we reject the null hypothesis? (Assume unequal variances. )