A microwave manufacturing company has just switched to a new automated production system.Unfortunately,the new machinery has been frequently failing and requiring repairs and service.The company has been able to provide its customers with a completion time of 6 days or less.To analyze whether the completion time has increased,the production manager took a sample of 36 jobs and found that the sample mean completion time was 6.5 days with a sample standard deviation of 1.5 days.At a significance level of .10,we can show that the completion time has increased.

Question

Quizplus · Accepted Answer

To test if the completion time has increased, we can perform a one-sample t-test with the null hypothesis being that the population mean completion time is equal to 6 days (since that was the previous completion time guaranteed to customers). The alternative hypothesis would be that the population mean completion time is greater than 6 days. Using a t-test with a significance level of .10 and 35 degrees of freedom (since n = 36), we find that the critical value is 1.310. The t-statistic for the sample is (6.5-6)/(1.5/sqrt(36)) = 2.00. Since 2.00 > 1.310, we can reject the null hypothesis and conclude that the completion time has increased with a significance level of .10. Therefore, the answer is A.

A Microwave Manufacturing Company Has Just Switched to a New