1. In a study of annual salaries of employees, random samples were selected from two companies to test if there is a difference in average salaries. For Company "X", the sample was size 65, the sample mean was $47,000 and the population standard deviation is assumed to be $11,000. For Company "Y", the sample size was 55, the sample mean was $44,000 and the population standard deviation is assumed to be $10,000. Test for a difference in average salaries at a 5% level of significance. What is your conclusion? 2. A poll was taken this year asking college students if they considered themselves overweight. A similar poll was taken 5 years ago. Five years ago, a sample of 270 students showed that 120 considered themselves overweight. This year a poll of 300 students showed that 140 considered themselves overweight. At a 5% level of significance, test to see if there is any difference in the proportion of college students who consider themselves overweight between the two polls. What is your conclusion? 3. The Acme Company manufactures large capacity Flash drives using two different manufacturing processes. The company is interested in determining if there is a significant difference in the average manufacturing time of the two processes. For Process #1, a sample of 28 items shows a sample mean of 9 minutes and a sample standard deviation of 3.5 minutes. For Process #2, a sample of 23 items shows a sample mean of 13 minutes and a sample standard deviation of 4.5 minutes. At a 5% level of significance, Test the claim of no difference in the average time for the two processes. What is your conclusion?
1. In a study of annual salaries of employees, random samples were selected from two companies to test if there is a difference in average salaries. For Company "X", the sample was size 65, the sample mean was $47,000 and the population standard deviation is assumed to be $11,000. For Company "Y", the
2. A poll was taken this year asking college students if they considered themselves overweight. A similar poll was taken 5 years ago. Five years ago, a sample of 270 students showed that 120 considered themselves overweight. This year a poll of 300 students showed that 140 considered themselves overweight. At a 5% level of significance, test to see if there is any difference in the proportion of college students who consider themselves overweight between the two polls. What is your conclusion?
3. The Acme Company manufactures large capacity Flash drives using two different manufacturing processes. The company is interested in determining if there is a significant difference in the average manufacturing time of the two processes. For Process #1, a sample of 28 items shows a sample mean of 9 minutes and a sample standard deviation of 3.5 minutes. For Process #2, a sample of 23 items shows a sample mean of 13 minutes and a sample standard deviation of 4.5 minutes. At a 5% level of significance, Test the claim of no difference in the average time for the two processes. What is your conclusion?
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