In 2010 the average duration of long distance calls originating in one town was 9.4 minutes.

In 2010 the average duration of long distance calls originating in one town was 9.4 minutes. A phone company wants to perform a hypothesis test to determine whether the average duration of long distance phone calls has changed from the 2010 mean of 9.4 minutes. The mean duration for a random sample of 50 calls originating in the town was 8.6 minutes. Does the data provide sufficient evidence to conclude that the mean call duration, u, is different from the 2010 mean of 9.4 minutes? Perform the appropriate test using a significance level of 0.01. Assume that o=4.8 minutes