The California State Highway Patrol recently conducted a study on a stretch of interstate highway south of San Francisco to determine whether the mean speed for California vehicles exceeded the mean speed for Nevada vehicles. A total of 140 California cars were included in the study, and 75 Nevada cars were included. Radar was used to measure the speed. The file Speed-Test contains the data collected by the California Highway Patrol.
a. Past studies have indicated that the speeds at which both Nevada and California drivers drive have normal distributions. Using a significance level equal to 0.10, obtain the results desired by the California Highway Patrol. Use a p -value approach to conduct the relevant hypothesis test. Discuss the results of this test in a short written statement.
b. Describe, in the context of this problem, what a Type I error would be.