A taxicab company has been receiving an increasing number of complaints concerning the delay time between when a call for a taxicab is received and when the passenger is picked up. The file TaxiDelays contains the delay times (in minutes) for two drivers on the same route for a period of 35 days.

Source: Data extracted from M. Sharma, “Above and Beyond,” Six Sigma Forum Magazine, May 2015, p. 21–25.

a. At the 0.05 level of significance, is there evidence of a difference in the variance of the delay times between the two drivers?

b. What assumption do you need to make in order to do (a)?

c. Evaluate the validity of the assumption in (a).

d. Based on the results of (a), which t-test for the difference between the means from Section 10.1 should you use to determine whether there is evidence of a difference in the mean delay time between the two drivers?