PROBLEM 4

The manager of the service department of a local car dealership has noted that the service times of a sample of 40 new automobiles has a population variance of 49 minutes.

1. Compute a 90% confidence interval estimate for the variance of the service times (in minutes) for all their new automobiles.
2. The manager of the service department of a local car dealership wants to test the claim that the variance of the service time is 36 minutes. Test this claim using a significance level of 0.01.