Question 1

The pooled proportion estimate is used when:

Accepted Answer

A) the proportion of successes from sample 1 equals the proportion of successes from sample 2. 
B) the total number of successes in both samples divided by the total of both sample sizes equals 1. 
C) the null hypothesis states that the two population proportions differ by some non-zero number. 
D) None of these choices. 
A) the proportion of successes from sample 1 equals the proportion of successes from sample 2. 
B) the total number of successes in both samples divided by the total of both sample sizes equals 1. 
C) the null hypothesis states that the two population proportions differ by some non-zero number. 
D) None of these choices.

Question 2

Which of the following statements is correct regarding the percentile points of the F-distribution?

Accepted Answer

A) F.05,10,20 = 1/F.95,10,20 
B) F.05,10,20 = 1/F.05,20,10 
C) F.95,10,20 = 1/F.05,20,10 
D) F.95,10,20 = 1/F.95,20,10 
A) F.05,10,20 = 1/F.95,10,20 
B) F.05,10,20 = 1/F.05,20,10 
C) F.95,10,20 = 1/F.05,20,10 
D) F.95,10,20 = 1/F.95,20,10

Question 3

The sampling distribution of the ratio of two sample variances is said to be F-distributed provided that we have two ____________________ samples drawn from their respective populations.

Accepted Answer

The answer of The sampling distribution of the ratio of...

Question 4

Clinic Waiting Time
 In a random sample of 20 patients who visited a clinic at Medical Center 1,a researcher found that the variance of the waiting time (in minutes)was 128.0.In a random sample of 15 patients in the clinic of Medical Center 2,the researcher found the variance to be 178.8. ​ ​
-{Clinic Waiting Time Narrative} Estimate with 95% confidence the ratio of the two population variances and interpret.

Accepted Answer

@#IMG-DLM& We estimate that th

Question 5

Random samples from two normal populations produced the following statistics:   ,   ,   ,and   .Is there enough evidence at the 5% significance level to infer that the variance of Population 1 is larger than the variance of Population 2?

Accepted Answer

@#IMG-DLM& . Rejection region: F > F_.05,9,14 = 2.65 Test s

Question 6

Worker Safety 
An OSHA agent wanted to determine if efforts to promote safety have been successful.By checking the records of 250 workers,he found that 30 of them suffered either minor or major injuries that year.A random sample of 400 workers last year revealed that 80 suffered some form of injury. ​ ​
-{Worker Safety Narrative} Estimate with 95% confidence the difference in population proportions.

Accepted Answer

−.08 ± .0562.Thus,LCL = −.1362

Question 7

Undergraduates' Test Scores
 35 undergraduate students who completed two years of college were asked to take a basic mathematics test.The mean and standard deviation of their scores were 75.1 and 12.8,respectively.In a random sample of 50 students who only completed high school,the mean and standard deviation of the test scores were 72.1 and 14.6,respectively. ​ ​
-{Undergraduates' Test Scores Narrative} Can we infer at the 10% significance level that a difference exists between the two groups?

Accepted Answer

@#IMG-DLM& , Rejection region: | t | > t_0.05,83 ≈ 1.664 T

Question 8

The degrees of freedom for a test of the mean of the paired differences is the number of ____________________ minus ____________________.

Accepted Answer

pairs; 1

Question 9

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

Accepted Answer

A) True 
 B)False

Question 10

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} Estimate with 90% confidence the mean difference and interpret.

Accepted Answer

−1.0 ± 1.587.Thus,LCL = −2.587,and UCL =

Question 11

Aptitude Test Scores 
Two random samples of 40 students were drawn independently from two populations of students.Assume their aptitude tests are normally distributed (total points = 100).The following statistics regarding their scores in an aptitude test were obtained:   . ​ ​
-{Aptitude Test Scores Narrative} Estimate with 95% confidence the difference between the two population means.

Accepted Answer

4 ± 3.25.Thus,LCL = .75,and UC

Question 12

In constructing a confidence interval estimate for the difference between the means of two independent normally distributed populations,we:

Accepted Answer

A) pool the sample variances when the unknown population variances are equal. 
B) pool the sample variances when the population variances are known and equal. 
C) pool the sample variances when the population means are equal. 
D) never pool the sample variances. 
A) pool the sample variances when the unknown population variances are equal. 
B) pool the sample variances when the population variances are known and equal. 
C) pool the sample variances when the population means are equal. 
D) never pool the sample variances.

Question 13

Which of the following statements is false for an F-distribution?

Accepted Answer

A) Variables that are F-distributed range from 0 to ∞. 
B) The exact shape of the distribution is determined by two numbers of degrees of freedom. 
C) The degrees of freedom for the numerator can be larger than,smaller than,or equal to the degrees of freedom for the denominator. 
D) All of these choices are true. 
A) Variables that are F-distributed range from 0 to ∞. 
B) The exact shape of the distribution is determined by two numbers of degrees of freedom. 
C) The degrees of freedom for the numerator can be larger than,smaller than,or equal to the degrees of freedom for the denominator. 
D) All of these choices are true.

Question 14

The pooled proportion estimate is found by taking the proportion of successes from sample 1 plus the proportion of successes from sample 2.

Accepted Answer

A) True 
 B)False

Question 15

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} Briefly explain what the interval estimate tells you.

Accepted Answer

We estimate that the proportio

Question 16

In testing for differences between the means of two independent populations the null hypothesis is:

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 17

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

Accepted Answer

@#IMG-DLM& We estimate that the ratio @#IMG-DLM& l

Question 18

In constructing a confidence interval estimate for the difference between two population proportions,we ____________________ (always/sometimes/never)pool the population proportions.

Accepted Answer

The answer of In constructing a confidence interval estimate for...

Question 19

The test for the equality of two population variances is based on the:

Accepted Answer

A) difference between the two sample variances. 
B) ratio of the two sample variances. 
C) sum of the two sample variances. 
D) product of the two sample variances. 
A) difference between the two sample variances. 
B) ratio of the two sample variances. 
C) sum of the two sample variances. 
D) product of the two sample variances.

Question 20

The number of degrees of freedom associated with the t-test,when the data are gathered from a matched pairs experiment with 8 pairs,is 7.

Accepted Answer

A) True 
 B)False

The pooled proportion estimate is used when:

Which of the following statements is correct regarding the percentile points of the F-distribution?

The sampling distribution of the ratio of two sample variances is said to be F-distributed provided that we have two ____________________ samples drawn from their respective populations.

Random samples from two normal populations produced the following statistics: , , ,and .Is there enough evidence at the 5% significance level to infer that the variance of Population 1 is larger than the variance of Population 2?

The degrees of freedom for a test of the mean of the paired differences is the number of minus .

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

In constructing a confidence interval estimate for the difference between the means of two independent normally distributed populations,we:

Which of the following statements is false for an F-distribution?

The pooled proportion estimate is found by taking the proportion of successes from sample 1 plus the proportion of successes from sample 2.

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} Briefly explain what the interval estimate tells you.

In testing for differences between the means of two independent populations the null hypothesis is:

In constructing a confidence interval estimate for the difference between two population proportions,we ____________________ (always/sometimes/never)pool the population proportions.

The test for the equality of two population variances is based on the:

The number of degrees of freedom associated with the t-test,when the data are gathered from a matched pairs experiment with 8 pairs,is 7.

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 pooled proportion estimate is used when:

Which of the following statements is correct regarding the percentile points of the F-distribution?

The sampling distribution of the ratio of two sample variances is said to be F-distributed provided that we have two ____________________ samples drawn from their respective populations.

Random samples from two normal populations produced the following statistics: , , ,and .Is there enough evidence at the 5% significance level to infer that the variance of Population 1 is larger than the variance of Population 2?

The degrees of freedom for a test of the mean of the paired differences is the number of ____________________ minus ____________________.

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

In constructing a confidence interval estimate for the difference between the means of two independent normally distributed populations,we:

Which of the following statements is false for an F-distribution?

The pooled proportion estimate is found by taking the proportion of successes from sample 1 plus the proportion of successes from sample 2.

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} Briefly explain what the interval estimate tells you.

In testing for differences between the means of two independent populations the null hypothesis is:

In constructing a confidence interval estimate for the difference between two population proportions,we ____________________ (always/sometimes/never)pool the population proportions.

The test for the equality of two population variances is based on the:

The number of degrees of freedom associated with the t-test,when the data are gathered from a matched pairs experiment with 8 pairs,is 7.

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 degrees of freedom for a test of the mean of the paired differences is the number of minus .

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

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} Briefly explain what the interval estimate tells you.