Exam 9: Testing the Difference Between Two Means, Two Variances, and Two Proportions

The critical value for a one-tailed right F -test is 2.57, when the degrees of freedom for the numerator = 15, and the degrees of freedom for the denominator = 20.

In testing the equality of the two means below, what is the test statistic? (Use the unequal variances formula.)

A reporter bought a hamburger at each of a set of random stores of two different restaurant chains.She then had the number of calories in each hamburger measured.Can the reporter conclude, at that the two sets of hamburgers have different amounts of calories? (Use the equal variances formula.)

A marketing firm asked a random set of married women and married men how much they were willing to spend for jewellery as a present for their spouse.Can the firm conclude, at , that Each of the two groups has a different willingness to spend? (Use the unequal variances formula.)

A marketing firm asked a random set of married and single men how much they were willing to spend for a vacation.At is a difference in the two amounts?

A study on the oxygen consumption rate (OCR) of sea cucumbers involved a random sample of size 10 at 15oC and a second random sample of size 7 kept at 18oC.If one tested the hypothesis that this range Of temperature had no effect on the OCR, the degrees of freedom for the test statistic would be (assume Equal variability)

Determine the 95% confidence interval of the true difference in the means.A sociologist wants to determine if the life expectancy of people in Africa is less than the life Expectancy of people in Asia.The data obtained is shown in the table below.Use 0.05.

A researcher wanted to determine if using an octane booster would increase gasoline mileage.A random sample of seven cars was selected; the cars were driven for two weeks without the booster and two weeks with the booster. -Determine the mean of the difference.

A field researcher is gathering data on the trunk diameters of mature pine and spruce trees in a certain area.The following are the results of his random sampling.Can he conclude, at that the average trunk diameter of a pine tree is greater than the average diameter of a spruce tree?

A conservationist wants to know if the water level (in meters) in Crab Lake is more or less variable than the water level in Gull Lake.If one tested the hypothesis that the levels are equally variable at 0.05, the hypothesis would be

If the test value in the figure below, for a test of the difference between two large sample means, is 2.57 when the critical value is 1.96, what decision about the hypothesis should be made?

For the samples summarized below, test the hypothesis at that the two variances are equal.

The formula for the f - test for comparing two means (independent samples, variances equal) is:

A dietician investigated whether apples turned brown at different rates when exposed to air after being washed in hot water or in cold water.She took 12 random apples and cut each in half.She washed one Half of each apple in hot water and the other half in cold water, and then put both halves out in a tray.Her Results (in hours until turning a particular shade of brown) are in the table below.At , did she see a Difference between the two treatments?

A local charity thinks that people in River Heights give more money to their charity than people in Lakeview.They conducted a survey of 24 people in each subdivision and recorded the results.Is their hypothesis correct? Let

For normally distributed populations, if two samples are independent and the variances are known, the z - test is used.

The campus bookstore asked a random set of freshmen and seniors how much they spent on textbooks for that term.The bookstore believes that the two groups spend the same amount.What is the test value?

The mean value of F is approximately equal to __________. ________________________________________

A conservationist wants to know if the average water level(in meters) in Horseshoe Lake is more than the average water level in Swan Lake.Test his hypothesis at =0.01.

Mauricio Tersignico, a local wine merchant, wants to determine if the average price of domestic wine is less than the average price of imported wine.The data obtained is shown in the table below. -What is the test value? Use (Use the variances unequal formula.)