In Problem 14.5 on page 583, horsepower and weight were used to predict miles per gallon (stored in Auto2010). Develop a regression model that includes horsepower, weight, and the interaction of horsepower and weight to predict miles per gallon.
a. At the 0.05 level of significance, is there evidence that the interaction term makes a significant contribution to the model?
b. Which regression model is more appropriate, the one used in this problem or the one used in Problem 14.5? Explain.