D Question 6 0.5 pts A production manager noticed that the mean time to complete a job was 160 minutes. The manager made some changes in the production process in an attempt to reduce the mean time to finish the job. From a sample of 12 times, we have x = 153.6, s =9.4. Determine whether the changes have decreased the mean completion time using 5% significance level. With of = 11, toos = 1.796. The rejection region is (1.796, co). The test statistic is t 160-153.6 The alternative hypothesis is u > 153.6. The null hypothesis is that the population mean is equal to 153.6. 153.6-160 Oth=- = -2.36. Since t*