Question

10) 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 25 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 .05, test whether the completion time has increased. ( form the hypotheses, show the critical and calculated values of the test statistic and perform the test)

Answer 1

n = 25

S =1.5

claim : The completion time has increased.

Null and alternative hypothesis is

It is a one-tailed test

Level of significance = 0.05

Here population standard deviation is not known so we use t-test statistic.

Test statistic is

Test statistic is

critical value

.

critical value =2.064

Test statistic critical value ,Failed to Reject Null hypothesis.

conclusion : There is insufficient evidence to conclude that the completion time has increased.