In a recent year, the mean wait for repairs for Verizon customers was 36 hours. In an effort to improve service, a new repair process was developed. This new process, when used on a sample of 90 repairs, resulted in a sample mean of 33 hours and a sample std. dev. of 10 hours.
(a) State the null and alternative hypotheses.
(b) Is there evidence that the change was successful in reducing the wait time? (use 0.05 level of significance)