10 STAT HWB q hypothesis testing two pops

# 10 STAT HWB q hypothesis testing two pops - Dr. V.R....

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Dr. V.R. Bencivenga Economics 329 PRACTICE ASSIGNMENT #10B: HYPOTHESIS TESTING II For each problem, state the null and alternative hypotheses in terms of the parameter(s) of probability model for the data, and give the test statistic; its sampling distribution; the reason why the sampling distribution is valid; the rejection region; and the conclusion of the test. 1. A consumer protection group conducted a study of two brands of tires, Beltex and Roadmaster. A random sample of tires of each brand was tested for durability by using a machine that wore down the tires until they blew out. The time it took (in hours) for each tire to blow out was recorded. Because the data were expensive to collect (in terms of time and ruined tires), small samples (15 of each brand) were used. The sample mean number of hours it took Beltex tires to blow out was 3.33, and the sample standard deviation was .68 hour. The sample mean number of hours it took Roadmaster tires to blow out was 3.98, and the sample standard deviation was .38 hour. a. Assuming that blowout times of each brand are approximately normally distributed and that the population standard deviations of blowout times are the same for the two brands of tires, test the null hypothesis that the population mean blowout times of the two brands are the same, against the alternative that they are different, using a 5% level of significance. b. The hypothesis test in part a assumes that the population standard deviations of blowout times are the same for Beltex and Roadmaster brand tires. Test this null hypothesis, against the alternative hypothesis that the population standard deviations are different. Use a 10% level of significance. 2.

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## 10 STAT HWB q hypothesis testing two pops - Dr. V.R....

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