For the Car and Driver information described in Exercise 17.9, it would seem reasonable that the number of seconds required to accelerate to 60 mph would depend on both a car’s weight and its horsepower.

Further, it would be logical to assume that horsepower and weight might interact. Using data file XR17009, with y 5 0–60 mph acceleration time (seconds), x1 5 horsepower, and x2 5 curb weight (pounds), fit a model of the form E(y) 5 0 1 1x1 1 2x2 1 3x1x2. Interpret the R2 value for the model and indicate whether, at the 0.02 level, the model is significant.