A microwave manufacturing company has just switched to a new automated production system. Unfortunately, the new machine

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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 6.4 days with a
sample standard deviation of 1.5 days. At a significance level of
0.01, test whether the completion time has increased. (Form the
hypotheses, show the critical and calculated values of the test
statistic and perform the test)