For Exercises 29–49, assume normality and use Welch's test and interval unless otherwise indicated.
30. Flight Delays. The U.S. Customs and Border Protection Agency keeps track of the flight delays at all U.S. international airports. The summary statistics for the waiting times at Los Angeles International Airport (Tom Bradley Terminal) on July 1, 2014 at 5 P.M. and at 11 P.M. are provided in the following table.
|
Waiting Times at 5 P.M. |
minutes |
minutes |
|
|
Waiting Times at 11 P.M. |
minutes |
minutes |
Test whether the mean waiting times at 5 P.M.are longer than those at 11 P.M., using level of significance .