TABLE 14-15
An automotive engineer would like to be able to predict automobile mileages. She believes that the two most important characteristics that affect mileage are horsepower and the number of cylinders (4 or 6) of a car. She believes that the appropriate model is
Y = 40 - 0.05X 1 + 20X 2 - 0.1X 1 X 2
where X 1 = horsepower
X 2 = 1 if 4 cylinders, 0 if 6 cylinders
Y = mileage.
-Referring to Table 14-15, the fitted model for predicting mileages for 4-cylinder cars is .
A) 60 - 0.15X1
B) 40 - 0.10X1
C) 40 - 0.05X1
D) 60 - 0.10X1

Question

TABLE 14-15 
An automotive engineer would like to be able to predict automobile mileages. She believes that the two most important characteristics that affect mileage are horsepower and the number of cylinders (4 or 6) of a car. She believes that the appropriate model is
Y = 40 - 0.05X 1 + 20X 2 - 0.1X 1 X 2 
where X 1 = horsepower
X 2 = 1 if 4 cylinders, 0 if 6 cylinders
Y = mileage.
-Referring to Table 14-15, the fitted model for predicting mileages for 4-cylinder cars is .
A) 60 - 0.15X1
B) 40 - 0.10X1
C) 40 - 0.05X1
D) 60 - 0.10X1

Quizplus · Accepted Answer

For 4-cylinder cars, XS1U1B12S1U1B0 = 1. Substituting into the model: Y = 40 - 0.05X1 + 20(1) - 0.1X1(1) = 60 - 0.15X1.

TABLE 14-15 An Automotive Engineer Would Like to Be Able to Predict