An intern for the California Transportation Department 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 out-of-state vehicles. A total of 140 California cars were included in the study, and 75 out-of-state cars were included. Radar was used to measure the speed.

The file Speed-Test contains the data.

a. Past studies have indicated that the speeds at which both out-of-state and California drivers drive have normal distributions. Use a p-value approach and an alpha = 0.10 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.