Chapter 12.2, Problem 3E

For Exercises 3 through 8, the null hypothesis was rejected. Use the Scheffe test when sample sizes are unequal or the Tukey test when sample sizes are equal, to test the differences between the pairs of means. Assume all variables are normally distributed, samples are independent, and the population variances are equal.

3. Exercise 9 in Section 12-1.

9. Hybrid Vehicles A study was done before the recent surge in gasoline prices to compare the cost to drive 25 miles for different types of hybrid vehicles. The cost of a gallon of gas at the time of the study was approximately $2.50. Based on the information given for different models of hybrid cars, trucks, and SUVs, is there sufficient evidence to conclude a difference m the mean cost to drive 25 miles? Use a = 0.05. (The information in this exercise will be used in Exercise 3 in Section 12-2.)

Hybrid cars	Hybrid SUVs	Hybrid trucks
2.10	2.10	3.62
2.70	2 42	3.43
1.67	2.25
167	2.10
1.30	2.25

Source: www.fueleconomy.com