Question 1

The degrees of freedom for the t-test used to compare two population means (independent samples)with unknown variances (assumed equal)will be n1 + n2 − 2.

Accepted Answer

A) True 
 B)False

Question 2

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 3

When using independent samples to test the difference between two population means,it is desirable but not necessary for the sample sizes to be the same.

Accepted Answer

A) True 
 B)False

Question 4

In a test for equality of two proportions,the sample proportions were p1 = 12/50 and p2 = 18/50.The test statistic is

Accepted Answer

A) −1.44 
B) −1.31 
C) −1.67 
D) Impossible to determine without knowing α. 
A) −1.44 
B) −1.31 
C) −1.67 
D) Impossible to determine without knowing α.

Question 5

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.A random sample of babies' weights (pounds)showed the following:   How many degrees of freedom would be used to test for a zero difference in means?

Accepted Answer

A) 4 
B) 8 
C) 10 
D) Must know α to say. 
A) 4 
B) 8 
C) 10 
D) Must know α to say.

Question 6

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.Random samples of 5 babies' weights (pounds)for each gender showed the following:   To test the researcher's hypothesis,we should use the

Accepted Answer

A) paired (dependent)samples t-test. 
B) independent samples t-test. 
C) large-sample z-test. 
D) t-test for correlation. 
A) paired (dependent)samples t-test. 
B) independent samples t-test. 
C) large-sample z-test. 
D) t-test for correlation.

Question 7

Group 1 has a mean of 13.4 and group 2 has a mean of 15.2.Both populations are known to have a variance of 9.0 and each sample consists of 18 items.What is the test statistic to test for equality of population means?

Accepted Answer

A) −1.755 
B) −1.643 
C) −1.800 
D) −1.285 
A) −1.755 
B) −1.643 
C) −1.800 
D) −1.285

Question 8

The t-test for two samples of paired data will use n differences,making it a one-sample t-test.

Accepted Answer

A) True 
 B)False

Question 9

Nacirema Airlines is buying a fleet of new fuel-efficient planes.The HogJet and the LitheJet both meet their price and performance needs,and both planes meet EPA noise guidelines.However,the quieter plane is preferred.Each plane is flown through a typical takeoff and landing sequence 10 times,while remote sensors at ground level record the noise levels (in decibels).The table below summarizes the sound level tests using Excel's default level of significance (α = .05).   If we switched from α = 0.05 to α = 0.005 in a two-tailed test of means,our assumption about variances (assumed equal or assumed unequal)would

Accepted Answer

A) affect the decision. 
B) not affect the decision. 
C) require a new analysis. 
A) affect the decision. 
B) not affect the decision. 
C) require a new analysis.

Question 10

In a test for equality of two proportions,the sample proportions were p1 = 12/50 and p2 = 18/50.The pooled proportion is

Accepted Answer

A) .20 
B) .24 
C) .36 
D) .30 
A) .20 
B) .24 
C) .36 
D) .30

Question 11

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,find the critical value for a right-tailed test at α = .05.

Accepted Answer

A) 1.960 
B) 1.645 
C) 2.326 
A) 1.960 
B) 1.645 
C) 2.326

Question 12

Assuming unequal variances in a t-test for a zero difference of two means,we would

Accepted Answer

A) sum the degrees of freedom for each sample. 
B) use the larger degrees of freedom for simplicity. 
C) use a complicated formula for the degrees of freedom. 
D) use a z-test to be conservative in the calculation. 
A) sum the degrees of freedom for each sample. 
B) use the larger degrees of freedom for simplicity. 
C) use a complicated formula for the degrees of freedom. 
D) use a z-test to be conservative in the calculation.

Question 13

Randomly chosen MBA students were asked their opinions about the ideal number of children for a married couple.The sample data were entered into MegaStat,and the following results were produced.   To compare the means,would it be appropriate to use a test that assumes equal variances?

Accepted Answer

A) Yes,because by pooling our variances,we can simplify our calculations. 
B) Yes,we should assume equal variances when comparing independent samples. 
C) No,because the sample statistics show that the variances are unequal at α = 0.05. 
D) No,because the variances will differ because the means differ significantly. 
A) Yes,because by pooling our variances,we can simplify our calculations. 
B) Yes,we should assume equal variances when comparing independent samples. 
C) No,because the sample statistics show that the variances are unequal at α = 0.05. 
D) No,because the variances will differ because the means differ significantly.

Question 14

Which Excel function would give a p-value for a left-tailed F test to compare two sample variances?

Accepted Answer

A) =1−F.DIST(s12/s22,df1,df2) 
B) =F.INV(α,df1,df2) 
C) =F.DIST(s12/s22,df1,df2) 
D) =F.INV(α/2,df1,df2) 
A) =1−F.DIST(s12/s22,df1,df2) 
B) =F.INV(α,df1,df2) 
C) =F.DIST(s12/s22,df1,df2) 
D) =F.INV(α/2,df1,df2)

Question 15

In general,the Welch-Satterthwaite t-test for two means has the same degrees of freedom as the pooled samples t-test for two means.

Accepted Answer

A) True 
 B)False

Question 16

Nacirema Airlines is buying a fleet of new fuel-efficient planes.The HogJet and the LitheJet both meet their price and performance needs,and both planes meet EPA noise guidelines.However,the quieter plane is preferred.Each plane is flown through a typical takeoff and landing sequence 10 times,while remote sensors at ground level record the noise levels (in decibels).The table below summarizes the sound level tests using Excel's default level of significance (α = .05).   In a left-tailed test comparing the means at α = .05,we would

Accepted Answer

A) not reject H0. 
B) reject H0. 
C) have insufficient information to make a decision. 
A) not reject H0. 
B) reject H0. 
C) have insufficient information to make a decision.

Question 17

In a random sample of patient records in Cutter Memorial Hospital,six-month postoperative exams were given in 90 out of 200 cases,while in Paymor Hospital such exams were given in 110 out of 200 cases.The pooled proportion is

Accepted Answer

A) .50 
B) .40 
C) .30 
D) .20 
A) .50 
B) .40 
C) .30 
D) .20

Question 18

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.   At α = .05,the two-tailed test for a difference in proportions is

Accepted Answer

A) just barely significant. 
B) not quite significant. 
C) not feasible due to nonnormality. 
A) just barely significant. 
B) not quite significant. 
C) not feasible due to nonnormality.

Question 19

A paired t-test with two columns of 10 observations in each column would use d.f.= 18.

Accepted Answer

A) True 
 B)False

Question 20

The critical value in an F test for equal variances is the ratio of the sample variances.

Accepted Answer

A) True 
 B)False

The degrees of freedom for the t-test used to compare two population means (independent samples)with unknown variances (assumed equal)will be n1 + n2 − 2.

When using independent samples to test the difference between two population means,it is desirable but not necessary for the sample sizes to be the same.

In a test for equality of two proportions,the sample proportions were p1 = 12/50 and p2 = 18/50.The test statistic is

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.A random sample of babies' weights (pounds)showed the following: How many degrees of freedom would be used to test for a zero difference in means?

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.Random samples of 5 babies' weights (pounds)for each gender showed the following: To test the researcher's hypothesis,we should use the

Group 1 has a mean of 13.4 and group 2 has a mean of 15.2.Both populations are known to have a variance of 9.0 and each sample consists of 18 items.What is the test statistic to test for equality of population means?

The t-test for two samples of paired data will use n differences,making it a one-sample t-test.

In a test for equality of two proportions,the sample proportions were p1 = 12/50 and p2 = 18/50.The pooled proportion is

Assuming unequal variances in a t-test for a zero difference of two means,we would

Randomly chosen MBA students were asked their opinions about the ideal number of children for a married couple.The sample data were entered into MegaStat,and the following results were produced. To compare the means,would it be appropriate to use a test that assumes equal variances?

Which Excel function would give a p-value for a left-tailed F test to compare two sample variances?

In general,the Welch-Satterthwaite t-test for two means has the same degrees of freedom as the pooled samples t-test for two means.

In a random sample of patient records in Cutter Memorial Hospital,six-month postoperative exams were given in 90 out of 200 cases,while in Paymor Hospital such exams were given in 110 out of 200 cases.The pooled proportion is

A paired t-test with two columns of 10 observations in each column would use d.f.= 18.

The critical value in an F test for equal variances is the ratio of the sample variances.

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

Chi-Square Tests

Filters

Exam 10: Two-Sample Hypothesis Tests

The degrees of freedom for the t-test used to compare two population means (independent samples)with unknown variances (assumed equal)will be n1 + n2 − 2.

When using independent samples to test the difference between two population means,it is desirable but not necessary for the sample sizes to be the same.

In a test for equality of two proportions,the sample proportions were p1 = 12/50 and p2 = 18/50.The test statistic is

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.A random sample of babies' weights (pounds)showed the following: How many degrees of freedom would be used to test for a zero difference in means?

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.Random samples of 5 babies' weights (pounds)for each gender showed the following: To test the researcher's hypothesis,we should use the

Group 1 has a mean of 13.4 and group 2 has a mean of 15.2.Both populations are known to have a variance of 9.0 and each sample consists of 18 items.What is the test statistic to test for equality of population means?

The t-test for two samples of paired data will use n differences,making it a one-sample t-test.

In a test for equality of two proportions,the sample proportions were p1 = 12/50 and p2 = 18/50.The pooled proportion is

Assuming unequal variances in a t-test for a zero difference of two means,we would

Randomly chosen MBA students were asked their opinions about the ideal number of children for a married couple.The sample data were entered into MegaStat,and the following results were produced. To compare the means,would it be appropriate to use a test that assumes equal variances?

Which Excel function would give a p-value for a left-tailed F test to compare two sample variances?

In general,the Welch-Satterthwaite t-test for two means has the same degrees of freedom as the pooled samples t-test for two means.

In a random sample of patient records in Cutter Memorial Hospital,six-month postoperative exams were given in 90 out of 200 cases,while in Paymor Hospital such exams were given in 110 out of 200 cases.The pooled proportion is

A paired t-test with two columns of 10 observations in each column would use d.f.= 18.

The critical value in an F test for equal variances is the ratio of the sample variances.

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

Chi-Square Tests

Filters