Question 1

The expected value of the difference of two sample means equals the difference of the corresponding population means when:

Accepted Answer

A) the populations are normally distributed. 
B) the samples are independent. 
C) the populations are approximately normal and the sample sizes are large. 
D) All of these choices are true. 
A) the populations are normally distributed. 
B) the samples are independent. 
C) the populations are approximately normal and the sample sizes are large. 
D) All of these choices are true.

Question 2

Two samples of sizes 25 and 20 are independently drawn from two normal populations,where the unknown population variances are assumed to be equal.The number of degrees of freedom of the equal-variances t-test statistic is 44.

Accepted Answer

A) True 
 B)False

Question 3

In testing the difference between the means of two normal populations using two independent samples when the population variances are unequal,the sampling distribution of the resulting statistic is:

Accepted Answer

A) normal. 
B) Student-t. 
C) approximately normal. 
D) approximately Student-t. 
A) normal. 
B) Student-t. 
C) approximately normal. 
D) approximately Student-t.

Question 4

The equal-variances test statistic of   is Student t-distributed with n1 + n2 − 2 degrees of freedom provided that the two populations are ____________________.

Accepted Answer

Question 5

Fitness Program
 A statistician wants to test for the equality of means in two independent samples drawn from normal populations of people enrolled in a fitness program.However,he will not perform the equal-variance t-test of the difference between the population means if the condition necessary for its use is not satisfied.The number of pound lost at the of the program data follow:   ​ ​
-{Fitness Program Narrative} Can the statistician conclude at the 5% significance level that the required condition is not satisfied?

Accepted Answer

@#IMG-DLM& . Rejection region: F > F_.025,7,9 = 4.20 or F <

Question 6

A Marine boot camp instructor recorded the time in which each of 15 recruits completed an obstacle course both before and after basic training.To test whether any improvement occurred,the instructor would use a t-distribution with 15 degrees of freedom.

Accepted Answer

A) True 
 B)False

Question 7

Senatorial Election
 A political poll immediately prior to a senatorial election reveals that 145 out of 250 male voters and 105 out of 200 female voters intend to vote for the Democrat candidate. ​ ​
-{Senatorial Election Narrative} What is the p-value of the test?

Accepted Answer

The answer of  Senatorial Election
 A political poll immediately...

Question 8

When testing the equality of two population variances the number in the null hypothesis is 0.

Accepted Answer

A) True 
 B)False

Question 9

When testing for the difference between two population variances with sample sizes of n1 = 8 and n2 = 10,the degrees of freedom are:

Accepted Answer

A) 8 and 10 
B) 7 and 9 
C) 2 and 18 
D) 18 and 2 
A) 8 and 10 
B) 7 and 9 
C) 2 and 18 
D) 18 and 2

Question 10

When comparing two population means using data that are gathered from a matched pairs experiment,the test statistic for μD is Student t-distributed with v = nD − 1 degrees of freedom,provided that the differences are normally distributed.

Accepted Answer

A) True 
 B)False

Question 11

TV Sex
 A survey of 1,500 Canadians reveals that 945 believe that there is too much sex on television.In a survey of 1,500 Americans,810 believe that there is too much television sex. ​ ​
-{TV Sex Narrative} Can we infer at the 99% significance level that the proportion of Canadians and Americans who believe that there is too much sex on television differ?

Accepted Answer

@#IMG-DLM& . Rejection region: | z | > z_.005 = 2.575 T

Question 12

Engine Wear
 To compare the wearing of two types of automobile engines,1 and 2,an experimenter chose to "pair" the measurements,comparing the wear for the two types of engines on each of 7 automobiles,as shown below.   ​ ​
-(Engine Wear Narrative} Determine whether these data are sufficient to infer at the 10% significance level that the two types of engines wear differently.

Accepted Answer

@#IMG-DLM& . (Tire 1 − Tire 2) Rejection region: |

Question 13

When comparing two population variances,we use the ratio   rather than the difference   .

Accepted Answer

A) True 
 B)False

Question 14

Antioxidants 
A food processor wants to compare two antioxidants for their effects on retarding spoilage.Suppose 16 cuts of fresh meat are treated with antioxidant A and 16 are treated with antioxidant B,and the number of hours until spoilage begins is recorded for each of the 32 cuts of meat.The results are summarized in the table below   ​ ​
-{Antioxidants Narrative} Develop the 95% confidence interval estimate of the ratio of the two population variances.

Accepted Answer

The answer of Antioxidants 
A food processor wants to compare...

Question 15

The pooled-variances t-test is used when the two population variances are ____________________.

Accepted Answer

The answer of The pooled-variances t-test is used when the...

Question 16

Promotional Campaigns 
The general manager of a chain of fast food chicken restaurants wants to determine how effective their promotional campaigns are.In these campaigns "20% off" coupons are widely distributed.These coupons are only valid for one week.To examine their effectiveness,the executive records the daily gross sales (in $1,000s)in one restaurant during the campaign and during the week after the campaign ends.The data is shown below.   ​ ​
-{Promotional Campaigns Narrative} Can they infer at the 5% significance level that sales increase during the campaign?

Accepted Answer

@#IMG-DLM& . (During − After) Rejection

Question 17

If the sample sizes are large enough so the conditions are met,the difference between two sample proportions has an approximate ____________________ distribution.

Accepted Answer

The answer of If the sample sizes are large enough...

Question 18

When testing for the equality of two population variances the number in the null hypothesis is ____________________.

Accepted Answer

The answer of When testing for the equality of two...

Question 19

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} Estimate with 95% confidence the ratio of the two population variances.

Accepted Answer

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

Question 20

In testing for the equality of two population variances,when the populations are normally distributed,the 5% level of significance has been used.To determine the rejection region,it will be necessary to refer to the F table corresponding to an upper-tail area of .05.

Accepted Answer

A) True 
 B)False

The expected value of the difference of two sample means equals the difference of the corresponding population means when:

Two samples of sizes 25 and 20 are independently drawn from two normal populations,where the unknown population variances are assumed to be equal.The number of degrees of freedom of the equal-variances t-test statistic is 44.

In testing the difference between the means of two normal populations using two independent samples when the population variances are unequal,the sampling distribution of the resulting statistic is:

The equal-variances test statistic of is Student t-distributed with n₁ + n₂ − 2 degrees of freedom provided that the two populations are ____________________.

A Marine boot camp instructor recorded the time in which each of 15 recruits completed an obstacle course both before and after basic training.To test whether any improvement occurred,the instructor would use a t-distribution with 15 degrees of freedom.

Senatorial Election A political poll immediately prior to a senatorial election reveals that 145 out of 250 male voters and 105 out of 200 female voters intend to vote for the Democrat candidate. -{Senatorial Election Narrative} What is the p-value of the test?

When testing the equality of two population variances the number in the null hypothesis is 0.

When testing for the difference between two population variances with sample sizes of n₁ = 8 and n₂ = 10,the degrees of freedom are:

When comparing two population means using data that are gathered from a matched pairs experiment,the test statistic for μ_D is Student t-distributed with v = n_D − 1 degrees of freedom,provided that the differences are normally distributed.

When comparing two population variances,we use the ratio rather than the difference .

The pooled-variances t-test is used when the two population variances are ____________________.

If the sample sizes are large enough so the conditions are met,the difference between two sample proportions has an approximate ____________________ distribution.

When testing for the equality of two population variances the number in the null hypothesis is ____________________.

In testing for the equality of two population variances,when the populations are normally distributed,the 5% level of significance has been used.To determine the rejection region,it will be necessary to refer to the F table corresponding to an upper-tail area of .05.

What Is Statistics

Graphical Descriptive Techniques 1

Graphical Descriptive Techniques 2

Numerical Descriptive Techniques

Data Collection and Sampling

Probability

Random Variables and Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions

Introduction to Estimation

Introduction to Hypothesis Testing

Inference About a Population

Analysis of Variance

Chi-Squared Tests

Simple Linear Regression and Correlation

Multiple Regression

Model Building

Nonparametric Statistics

Time-Series Analytics and Forecasting

Statistical Process Control

Decision Analysis

Conclusion

Filters

Exam 13: Inference About Comparing Two Populations

The expected value of the difference of two sample means equals the difference of the corresponding population means when:

Two samples of sizes 25 and 20 are independently drawn from two normal populations,where the unknown population variances are assumed to be equal.The number of degrees of freedom of the equal-variances t-test statistic is 44.

In testing the difference between the means of two normal populations using two independent samples when the population variances are unequal,the sampling distribution of the resulting statistic is:

The equal-variances test statistic of is Student t-distributed with n1 + n2 − 2 degrees of freedom provided that the two populations are ____________________.

A Marine boot camp instructor recorded the time in which each of 15 recruits completed an obstacle course both before and after basic training.To test whether any improvement occurred,the instructor would use a t-distribution with 15 degrees of freedom.

Senatorial Election A political poll immediately prior to a senatorial election reveals that 145 out of 250 male voters and 105 out of 200 female voters intend to vote for the Democrat candidate. ​ ​ -{Senatorial Election Narrative} What is the p-value of the test?

When testing the equality of two population variances the number in the null hypothesis is 0.

When testing for the difference between two population variances with sample sizes of n1 = 8 and n2 = 10,the degrees of freedom are:

When comparing two population means using data that are gathered from a matched pairs experiment,the test statistic for μD is Student t-distributed with v = nD − 1 degrees of freedom,provided that the differences are normally distributed.

When comparing two population variances,we use the ratio rather than the difference .

The pooled-variances t-test is used when the two population variances are ____________________.

If the sample sizes are large enough so the conditions are met,the difference between two sample proportions has an approximate ____________________ distribution.

When testing for the equality of two population variances the number in the null hypothesis is ____________________.

In testing for the equality of two population variances,when the populations are normally distributed,the 5% level of significance has been used.To determine the rejection region,it will be necessary to refer to the F table corresponding to an upper-tail area of .05.

What Is Statistics

Graphical Descriptive Techniques 1

Graphical Descriptive Techniques 2

Numerical Descriptive Techniques

Data Collection and Sampling

Probability

Random Variables and Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions

Introduction to Estimation

Introduction to Hypothesis Testing

Inference About a Population

Analysis of Variance

Chi-Squared Tests

Simple Linear Regression and Correlation

Multiple Regression

Model Building

Nonparametric Statistics

Time-Series Analytics and Forecasting

Statistical Process Control

Decision Analysis

Conclusion

Filters

The equal-variances test statistic of is Student t-distributed with n₁ + n₂ − 2 degrees of freedom provided that the two populations are ____________________.

Senatorial Election A political poll immediately prior to a senatorial election reveals that 145 out of 250 male voters and 105 out of 200 female voters intend to vote for the Democrat candidate. -{Senatorial Election Narrative} What is the p-value of the test?

When testing for the difference between two population variances with sample sizes of n₁ = 8 and n₂ = 10,the degrees of freedom are:

When comparing two population means using data that are gathered from a matched pairs experiment,the test statistic for μ_D is Student t-distributed with v = n_D − 1 degrees of freedom,provided that the differences are normally distributed.