Question 1

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 2

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 0.05.

Accepted Answer

A) True 
 B)False

Question 3

For testing the difference between two population proportions, the pooled proportion estimate is found by taking:

Accepted Answer

A)  the proportion of successes from sample 1 plus the proportion of successes from sample 2. 
B)  the total number of successes in both samples divided by the total of both sample sizes. 
C)  the difference between the proportion of successes in each sample. 
D)  None of these choices. 
A)  the proportion of successes from sample 1 plus the proportion of successes from sample 2. 
B)  the total number of successes in both samples divided by the total of both sample sizes. 
C)  the difference between the proportion of successes in each sample. 
D)  None of these choices.

Question 4

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

Accepted Answer

A) True 
 B)False

Question 5

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

Accepted Answer

A)  Variables that are F-distributed range from 0 to $\infty$. 
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 $\infty$. 
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 6

Two independent samples are drawn from two normal populations, where the population variances are assumed to be equal. The sampling distribution of the ratio of the two sample variances is:

Accepted Answer

A)  normal 
B)  Student-t 
C)  F 
D)  chi-squared 
A)  normal 
B)  Student-t 
C)  F 
D)  chi-squared

Question 7

The variance of the difference between two sample proportions equals the ____________________ of their population proportion variances.

Accepted Answer

The answer of The variance of the difference between two...

Question 8

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 9

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& vs. @#IMG-DLM& Rejection region: F > F_0.05,9,14 = 2.65 Tes

Question 10

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.
-Briefly describe what the interval estimate tells you.

Accepted Answer

We estimate that the

Question 11

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

Accepted Answer

A) True 
 B)False

Question 12

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.
-Estimate with 95% confidence the difference in population proportions.

Accepted Answer

-0.08 @#LAT-DLM& 0.0562. Thus, LCL = -0.

Question 13

The statistical distribution used for testing the difference between two population variances is the

Accepted Answer

A)  Student t-distribution 
B)  standard normal distribution 
C)  F-distribution 
D)  None of these choices. 
A)  Student t-distribution 
B)  standard normal distribution 
C)  F-distribution 
D)  None of these choices.

Question 14

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.
  
-Estimate with 95% confidence the difference in population proportions.

Accepted Answer

0.08 @#LAT-DLM& 0.0877. Thus,

Question 15

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.
-Estimate with 95% confidence the difference in the proportion of male and female voters who intend to vote for the Democrat candidate.

Accepted Answer

0.055 @#LAT-DLM&0.0924. Thus, LCL = -0.0374, and U

Question 16

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.
-Can we infer at the 5% significance level that the proportions of male and female voters who intend to vote for the Democrat candidate differ?

Accepted Answer

@#IMG-DLM& vs. @#IMG-DLM& Rejection region: | z | > z_.025 = 1.96

Question 17

All F-tests for the equality of two population variances are one-tailed tests.

Accepted Answer

A) True 
 B)False

Question 18

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 19

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 completion of the program data follow:
  
-Can the statistician conclude at the 5% significance level that the required condition is not satisfied?

Accepted Answer

@#IMG-DLM& vs. @#IMG-DLM& Rejection region: F > F_0.025,7,9 = 4.20 or

Question 20

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
  
-Calculate the value of the test statistic for testing the equality of the population variances, and write the proper conclusion.

Accepted Answer

@#IMG-DLM& . Since F is not larger than

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 0.05.

For testing the difference between two population proportions, the pooled proportion estimate is found by taking:

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

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

Two independent samples are drawn from two normal populations, where the population variances are assumed to be equal. The sampling distribution of the ratio of the two sample variances is:

The variance of the difference between two sample proportions equals the ____________________ of their population proportion variances.

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

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?

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

The statistical distribution used for testing the difference between two population variances is the

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. -Estimate with 95% confidence the difference in population proportions.

All F-tests for the equality of two population variances are one-tailed tests.

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

What Is Statistics

Graphical and Tabular Descriptive Techniques

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

Inference About Comparing Two Populations, Part 1

Analysis of Variance

Chi-Squared Tests

Simple Linear Regression and Correlation

Multiple Regression

Review of Statistical Inference

Filters

Exam 13: Inference About Comparing Two Populations, Part 2

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 0.05.

For testing the difference between two population proportions, the pooled proportion estimate is found by taking:

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

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

Two independent samples are drawn from two normal populations, where the population variances are assumed to be equal. The sampling distribution of the ratio of the two sample variances is:

The variance of the difference between two sample proportions equals the ____________________ of their population proportion variances.

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

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?

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

The statistical distribution used for testing the difference between two population variances is the

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. -Estimate with 95% confidence the difference in population proportions.

All F-tests for the equality of two population variances are one-tailed tests.

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

What Is Statistics

Graphical and Tabular Descriptive Techniques

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

Inference About Comparing Two Populations, Part 1

Analysis of Variance

Chi-Squared Tests

Simple Linear Regression and Correlation

Multiple Regression

Review of Statistical Inference

Filters

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