A large metropolitan police force is considering changing from full-size to mid-size cars. The police force sampled cars from each of three manufacturers. The number sampled represents the number that the manufacturer was able to provide for the test. Each car was driven for 5,000 miles, and the operating cost per mile was computed. The operating costs, in cents per mile, for the 12 cars are provided in the file Police. Perform the appropriate ANOVA test on these data. Assume a significance level of 0.05. State the appropriate null and alternative hypotheses. Do the experimental data provide evidence that the median operating costs per mile for the three types of police cars are different?