13.4 A sample of small cars was selected, and the values of x 5 horsepower and y 5 fuel efficiency (mpg) were determined for each car. Fitting the simple linear regression model gave the estimated regression equation y⁄

5 44.0 2 .150x.

a. How would you interpret b 5 2.150?

b. Substituting x 5 100 gives y⁄

5 29.0. Give two different interpretations of this number.

c. What happens if you predict efficiency for a car with a 300-horsepower engine? Why do you think this has occurred?

d. Interpret r2 5 0.680 in the context of this problem.

e. Interpret se 5 3.0 in the context of this problem.