Exam 10: Two-Sample Hypothesis Tests

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.What is the z test statistic?

A medical researcher compared the variances in birth weights for five randomly chosen babies of each gender,with the MegaStat results shown below. The population variances

If the sample proportions were p1 = 12/50 and p2 = 18/50,what is the approximate 95 percent confidence interval for the difference of the population proportions?

A psychology researcher has a theory that predicts women will tend to carry more cash than men.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.The test statistic for the researcher's hypothesis is

If the sample proportions are p1 = 6/90 and p2 =4/100,normality may be assumed in a test comparing the two population proportions.

Which is not true of the two-tailed F-test for equality of variances?

John wants to compare two means.His sample statistics were 1 = 22.7,s12 = 5.4,n1 = 9 and 2 = 20.5,s22 = 3.6,n2 = 9.Assuming equal variances,which is the approximate 95 percent confidence interval for the difference of the population means?

The difference between two sample proportions p1 − p2 may be assumed normally distributed if each sample has at least 10 "successes" and 10 "failures."

In a test of a new surgical procedure,the five most respected surgeons in FlatBroke Township were invited to Carver Hospital.Each surgeon was assigned two patients of the same age,gender,and overall health.One patient was operated upon in the old way,and the other in the new way.Both procedures are considered equally safe.The surgery times are shown below: Which test should we use to test for zero difference in mean times? Which test should we use to test for zero difference in mean times?

If the population variances are exactly equal,the sample F test statistic will be zero.

The F test is used to test for the equality of two population variances.

The table below shows the mean number of daily errors by air traffic controller trainees during the first two weeks on the job.We want to perform a paired t-test at α = .05 to see if the mean daily errors decreased significantly. What would be the degrees of freedom for the appropriate test?

The table below shows two samples taken to compare the mean age of individuals who purchased the iPhone 3G at two AT&T store locations. What are the critical values for a two-tailed test for equal variances at α = .05?

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

The coach of an adult Master's Swim class selected eight swimmers within each of the two age groups shown below.A 50-yard freestyle time is recorded for each swimmer.The resulting times (seconds)are shown below.Which statistical test would you choose to compare the two groups?

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).The pooled proportion for a test to compare the two proportions would be

In a test of a new surgical procedure,the five most respected surgeons in FlatBroke Township were invited to Carver Hospital.Each surgeon was assigned two patients of the same age,gender,and overall health.One patient was operated upon in the old way,and the other in the new way.Both procedures are considered equally safe.The surgery times are shown below: The time (in minutes)to complete each procedure was carefully recorded.In a right-tailed test for a difference of means,the test statistic is

A certain psychological theory predicts that men want bigger families than women.Kate asked each student in her psychology class how many children he or she considered ideal for a married couple and obtained the Excel results shown below at α = .05. What conclusion can you draw in a two-tailed test at α = .05?

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). After inspecting this table,we would most likely

In a random sample of patient records in Cutter Memorial Hospital,six-month postoperative exams were given in 90 out of 200 prostatectomy patients,while in Paymor Hospital such exams were given in 110 out of 200 cases.In comparing these two proportions,normality of the difference may be assumed because