A corporation is trying to decide which of three makes of automobile to order for its fleet—domestic, Japanese, or European. Five cars of each type were ordered, and, after 10,000 miles of driving,...

A corporation is trying to decide which of three makes of automobile to order for its fleet—domestic, Japanese, or European. Five cars of each type were ordered, and, after 10,000 miles of driving, the operating cost per mile of each was assessed. The accompanying results in cents per mile were obtained.

Domestic    Japanese    European

   18.0              20.1          19.3

   15.6              15.6          15.4

   15.4              16.1          15.1

   19.1              15.3          18.6

   16.9              15.4          16.1



a. Prepare the analysis of variance table for these data.

b. Test the null hypothesis that the population mean operating costs per mile are the same for these three types of car.

c. Compute the minimum significant difference and indicate which subgroups have different means.