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Hypothesis Testing 0802-HTExample1.doc Page 1 of 3 Drug Testing of Job Applicants. In 1990, 5.8% of job applicants who were tested for drugs failed the test. At the 0.01 significance level, test the claim that the failure rate is now lower if a simple random sample of 1520 current job applicants results in 58 failures (based on data from the American Management Association). Does the result suggest that fewer job applicants now use drugs? [NOTE: Both examples are from the 8th edition of Elementary Statistics by Triola. Publisher: Pearson/Addison-Wesley. Hypothesis Testing 0802-HTExample1.doc Page 2 of 3 Mean Time for 4-Year Degree. Kim is a high school senior who is concerned about attending college because she knows that many college students require more than four years to earn a bachelor’s degree. At the 0.10 significance level, test the claim of her guidance counselor, who states that the mean time is greater than 5 years. Sample data consist of a mean of 5.15 years and a standard deviation of 1.68 years fro 80 randomly selected college graduates (based on data from the National Center for Education Statistics). Hypothesis Testing 0802-HTExample1.doc Page 3 of 3 Heights of Women. According to Gordon, Churchill, et al., women have heights with a mean of 64.1 in. and a standard deviation of 2.52 in. Using the sample of heights of women in Data Set 1 in Appendix B, test the claim that the standard deviation is 2.52 in. Use a 0.05 significance level. When designing car seats for women, what would be a consequence of believing that heights of women vary less than they really vary? From Data Set 1, we find the sample mean to be 63.195 in. and the sample standard deviation to be 2.741228 in. Testing the claim that the standard deviation in heights is equal to 2.52 in. yields the conclusion that we should fail to reject the null hypothesis. Therefore, the “sample does not provide enough evidence to reject the claim” that the standard deviation is 2.52 in.