A sample of 48 different departures delay times (in minutes) for American Airlines from New York to Los Angeles has a mean of 10.5 minutes and a standard deviation of 30.8 minutes. Use a 0.01...

A sample of 48 different departures delay times (in minutes) for American Airlines from New York to Los Angeles has a mean of 10.5 minutes and a standard deviation of 30.8 minutes. Use a 0.01 significance level to test the claim that the mean departure delay time for all such flights is less than 12 minutes. Is a flight operations manager justified in reporting that the mean departure is less than 12 minutes?