Exam 10: Two-Sample Hypothesis Tests

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. What conclusion can you draw from this analysis at α = .05?

An F-test for equality of variances gives a p-value of .003.At α = .05,what conclusion can be made about the preferred test to compare the means for the same sample?

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

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?

Jason wants to perform a two-tailed test for equality between two independent sample proportions.Each sample has at least 10 "successes" and 10 "failures." Jason's test statistic is -1.44.What is his p−value?

A new policy of "flex hours" is proposed.Random sampling showed that 28 of 50 female workers favored the change,while 22 of 50 male workers favored the change.Management wonders if there is a difference between the two groups.What is the p-value for a two-tailed test?

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 α = .10 in a two-tailed test,we conclude that

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-tailed test for equal means (assume equal variances),the critical value at α = .10 is

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-tailed test of means (assume equal variances),the test statistic is

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.She weighed a random sample of five babies of each gender.Their weights (pounds)are shown below,along with some MegaStat results. The population means

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-tailed test of equal means (assume equal variances),the pooled variance is

Of 200 youthful gamers (under 18)who tried the new Z-Box-Plus game,160 rated it "excellent," compared with only 144 of 200 adult gamers (18 or over).Calculate the 95 percent confidence interval for the difference of proportions.

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.The p-value for a left-tailed test is approximately

In a left-tailed test comparing two means with unknown variances assumed to be equal,the test statistic was t = −1.81 with sample sizes of n1 = 8 and n2 = 12.The p-value would be

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.In a right-tailed test,the p-value is .0274,so at α = .025 we should

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 6 males had a mean of $17.30 with a standard deviation of $9.60.The value of the test statistic for a folded F-test for equal variances is

A corporate analyst is testing whether mean inventory turnover has increased.Inventory turnover in six randomly chosen product distribution centers (PDCs)is shown. The degrees of freedom for the appropriate test would be

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

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.At α = .05,in a left-tailed test,the critical value to compare the means (assuming equal variances)is

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