Question 1

In an F test for the ratio of two population variances,the degrees of freedom in both the numerator and the denominator must be equal.

Accepted Answer

A) True 
 B)False

Question 2

Does the Speedo Fastskin II Male Hi-Neck Bodyskin competition racing swimsuit improve a swimmer's 200-yard individual medley performance times? A test of 100 randomly chosen male varsity swimmers at several different universities showed that 66 enjoyed improved times,compared with only 54 of 100 female varsity swimmers.To test for equality in the proportions of men versus women who experienced improvement,the test statistic is approximately:

Accepted Answer

A)  1.73 
B)  1.47 
C)  2.31 
D)  Can't tell without knowing the tail of the test. 
A)  1.73 
B)  1.47 
C)  2.31 
D)  Can't tell without knowing the tail of the test.

Question 3

Litter sizes (number of pups)for randomly chosen dogs from two breeds were compared.The sample data were entered into Excel,and the following results were produced. What is the critical value for a left-tailed test comparing the means at F1F1F1S1F1F1F10 = .05?

Accepted Answer

A)  -1.645 
B)  -1.721 
C)  -1.703 
D)  -1.699 
A)  -1.645 
B)  -1.721 
C)  -1.703 
D)  -1.699

Question 4

Does the Speedo Fastskin II Male Hi-Neck Bodyskin competition racing swimsuit improve a swimmer's 200-yard individual medley performance times? A test of 100 randomly chosen male varsity swimmers at several different universities showed that 66 enjoyed improved times,compared with only 54 of 100 female varsity swimmers.In comparing the proportions of males versus females,is it safe to assume normality?

Accepted Answer

A)  Yes,clearly. 
B)  Yes,but just barely. 
C)  No. 
D)  Can't tell without knowing F1F1F1S1F1F1F10. 
A)  Yes,clearly. 
B)  Yes,but just barely. 
C)  No. 
D)  Can't tell without knowing F1F1F1S1F1F1F10.

Question 5

Management of Melodic Kortholt Company compared absenteeism rates in two plants on the third Monday in November.Of Plant A's 800 employees,120 were absent.Of Plant B's 1200 employees,144 were absent.MegaStat's results for a two-tailed test are shown below. The test statistic (shown as z = x.xx)is approximately:

Accepted Answer

A)  2.022 
B)  1.960 
C)  1.942 
D)  1.645 
A)  2.022 
B)  1.960 
C)  1.942 
D)  1.645

Question 6

Which of the following is not a characteristic of the F distribution?

Accepted Answer

A)  It is a continuous distribution. 
B)  It is always a positive number. 
C)  It is a family based on two sets of degrees of freedom. 
D)  It describes the ratio of two sample means. 
A)  It is a continuous distribution. 
B)  It is always a positive number. 
C)  It is a family based on two sets of degrees of freedom. 
D)  It describes the ratio of two sample means.

Question 7

In conducting a paired t-test of the difference between two population means,the usual null hypothesis is that the mean of the population of paired differences is zero.

Accepted Answer

A) True 
 B)False

Question 8

If the sample proportions are p1 = 15/60 and p2 = 20/90,normality may be assumed in a test comparing the two population proportions.

Accepted Answer

A) True 
 B)False

Question 9

We could use the same data set for two independent samples (i.e. ,two columns of data)either to compare the means (t-test)or to compare the variances (F test).

Accepted Answer

A) True 
 B)False

Question 10

Carver Memorial Hospital's surgeons have a new procedure that they think will decrease the time to perform an appendectomy.A sample of 8 appendectomies using the old method had a mean of 38 minutes with a variance of 36 minutes,while a sample of 10 appendectomies using the experimental method had a mean of 29 minutes with a variance of 16 minutes.For a right-tail test of means (assume equal variances),the test statistic is:

Accepted Answer

A)  3.814 
B)  2.365 
C)  3.000 
D)  1.895 
A)  3.814 
B)  2.365 
C)  3.000 
D)  1.895

Question 11

At Huge University,a sample of 200 business school seniors showed that 26 planned to pursue an MBA degree,compared with 120 of 800 arts and sciences seniors.We want to know if the proportion is higher in the arts and sciences group.For this test,the assumption of normality for the difference of proportions is:

Accepted Answer

A)  clearly unjustified. 
B)  clearly justified. 
C)  a borderline call. 
A)  clearly unjustified. 
B)  clearly justified. 
C)  a borderline call.

Question 12

Carver Memorial Hospital's surgeons have a new procedure that they think will decrease the time to perform an appendectomy.A sample of 8 appendectomies using the old method had a mean of 38 minutes with a variance of 36 minutes,while a sample of 10 appendectomies using the experimental method had a mean of 29 minutes with a variance of 16 minutes.For a right-tail test for equal means (assume equal variances),the critical value at F1F1F1S1F1F1F10 = .10 is:

Accepted Answer

A)  1.746 
B)  1.337 
C)  2.120 
D)  2.754 
A)  1.746 
B)  1.337 
C)  2.120 
D)  2.754

Question 13

Two well-known aviation training schools are being compared using random samples of their graduates.It is found that 70 of 140 graduates of Fly-More Academy passed their FAA exams on the first try,compared with 104 of 260 graduates of Blue Yonder Institute.To compare the pass rates,the p-value for a right-tailed test is approximately:

Accepted Answer

A)  .054 
B)  .027 
C)  .155 
D)  .013 
A)  .054 
B)  .027 
C)  .155 
D)  .013

Question 14

When using independent samples to test the difference between two population means,a pooled variance is used if the population variances are unknown and assumed equal.

Accepted Answer

A) True 
 B)False

Question 15

During a test period,an experimental group of 10 vehicles using an 85 percent ethanol-gasoline mixture showed mean CO2 emissions of 667 pounds per 1000 miles,with a standard deviation of 20 pounds.A control group of 14 vehicles using regular gasoline showed mean CO2 emissions of 679 pounds per 1000 miles with a standard deviation of 15 pounds.Assuming equal variances,the pooled variance is:

Accepted Answer

A)  296.59 
B)  225.00 
C)  400.00 
D)  522.16 
A)  296.59 
B)  225.00 
C)  400.00 
D)  522.16

Question 16

A random sample of Ersatz University students revealed that 16 females had a mean of $22.30 in their wallets with a standard deviation of $3.20,while 16 males had a mean of $17.30 with a standard deviation of $9.60.In comparing the population variances at F1F1F1S1F1F1F10 = .10 in a two-tailed test,we conclude that:

Accepted Answer

A)  the variances are equal. 
B)  the variances are unequal. 
C)  the variances are incomparable (different sample sizes). 
A)  the variances are equal. 
B)  the variances are unequal. 
C)  the variances are incomparable (different sample sizes).

Question 17

In a left-ailed test comparing two means with variances unknown but assumed to be equal,the sample sizes were n1 = 8 and n2 = 12.At F1F1F1S1F1F1F10 = .05,the critical value would be:

Accepted Answer

A)  -1.960 
B)  -2.101 
C)  -1.734 
D)  -1.645 
A)  -1.960 
B)  -2.101 
C)  -1.734 
D)  -1.645

Question 18

Random samples of students were compared to see whether or not there was a difference in the proportion favoring the university's proposed switch from MWF (three-day)classes to MW and TR (two-day)classes.The results shown below are from MegaStat.Analyze these results thoroughly.

Accepted Answer

The large test statistic (z = -4.000)and

Question 19

Two well-known aviation training schools are being compared using random samples of their graduates.It is found that 70 of 140 graduates of Fly-More Academy passed their FAA exams on the first try,compared with 104 of 260 graduates of Blue Yonder Institute.To compare the two proportions,the assumption of normality of the test statistic is:

Accepted Answer

A)  justified,but it is a borderline case. 
B)  clearly justified. 
C)  clearly not justified. 
A)  justified,but it is a borderline case. 
B)  clearly justified. 
C)  clearly not justified.

Question 20

Mary analyzed occupancy rates at two community hospitals and obtained the following Excel results. Which conclusion is correct in a two-tailed test at F1F1F1S1F1F1F10 = .05?

Accepted Answer

A)  There appears to be no difference in the mean occupancy rates. 
B)  HealthPro has a significantly higher mean occupancy rate. 
C)  There is a significant difference in the mean occupancy rates. 
A)  There appears to be no difference in the mean occupancy rates. 
B)  HealthPro has a significantly higher mean occupancy rate. 
C)  There is a significant difference in the mean occupancy rates.

In an F test for the ratio of two population variances,the degrees of freedom in both the numerator and the denominator must be equal.

Litter sizes (number of pups)for randomly chosen dogs from two breeds were compared.The sample data were entered into Excel,and the following results were produced. What is the critical value for a left-tailed test comparing the means at  = .05?

Which of the following is not a characteristic of the F distribution?

In conducting a paired t-test of the difference between two population means,the usual null hypothesis is that the mean of the population of paired differences is zero.

If the sample proportions are p₁ = 15/60 and p₂ = 20/90,normality may be assumed in a test comparing the two population proportions.

We could use the same data set for two independent samples (i.e. ,two columns of data)either to compare the means (t-test)or to compare the variances (F test).

When using independent samples to test the difference between two population means,a pooled variance is used if the population variances are unknown and assumed equal.

In a left-ailed test comparing two means with variances unknown but assumed to be equal,the sample sizes were n₁ = 8 and n₂ = 12.At  = .05,the critical value would be:

Random samples of students were compared to see whether or not there was a difference in the proportion favoring the university's proposed switch from MWF (three-day)classes to MW and TR (two-day)classes.The results shown below are from MegaStat.Analyze these results thoroughly.

Mary analyzed occupancy rates at two community hospitals and obtained the following Excel results. Which conclusion is correct in a two-tailed test at  = .05?

Overview of Statistics

Data Collection

Describing Data Visually

Descriptive Statistics

Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions and Estimation

One-Sample Hypothesis Tests

Analysis of Variance

Simple Regression

Multiple Regression

Time-Series Analysis

Chi-Square Tests

Nonparametric Tests

Quality Management

Filters

Exam 10: Two-Sample Hypothesis Tests

In an F test for the ratio of two population variances,the degrees of freedom in both the numerator and the denominator must be equal.

Litter sizes (number of pups)for randomly chosen dogs from two breeds were compared.The sample data were entered into Excel,and the following results were produced. What is the critical value for a left-tailed test comparing the means at  = .05?

Which of the following is not a characteristic of the F distribution?

In conducting a paired t-test of the difference between two population means,the usual null hypothesis is that the mean of the population of paired differences is zero.

If the sample proportions are p1 = 15/60 and p2 = 20/90,normality may be assumed in a test comparing the two population proportions.

We could use the same data set for two independent samples (i.e. ,two columns of data)either to compare the means (t-test)or to compare the variances (F test).

When using independent samples to test the difference between two population means,a pooled variance is used if the population variances are unknown and assumed equal.

In a left-ailed test comparing two means with variances unknown but assumed to be equal,the sample sizes were n1 = 8 and n2 = 12.At  = .05,the critical value would be:

Random samples of students were compared to see whether or not there was a difference in the proportion favoring the university's proposed switch from MWF (three-day)classes to MW and TR (two-day)classes.The results shown below are from MegaStat.Analyze these results thoroughly.

Mary analyzed occupancy rates at two community hospitals and obtained the following Excel results. Which conclusion is correct in a two-tailed test at  = .05?

Overview of Statistics

Data Collection

Describing Data Visually

Descriptive Statistics

Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions and Estimation

One-Sample Hypothesis Tests

Analysis of Variance

Simple Regression

Multiple Regression

Time-Series Analysis

Chi-Square Tests

Nonparametric Tests

Quality Management

Filters

If the sample proportions are p₁ = 15/60 and p₂ = 20/90,normality may be assumed in a test comparing the two population proportions.

In a left-ailed test comparing two means with variances unknown but assumed to be equal,the sample sizes were n₁ = 8 and n₂ = 12.At  = .05,the critical value would be: