Instruction 13 -Referring to Instruction 13

Multiple Choice

Instruction 13.41
An automotive engineer would like to be able to predict automobile fuel economy. She believes that the two most important characteristics that affect economy are engine power and the number of cylinders (4 or 6) of a car. She believes that the appropriate model is
$\begin{array}{l}Y = 40 - 0.05 X _ { 1 } + 20 X _ { 2 } - 0.1 X _ { 1 } X _ { 2 }\\\\\text { where } \begin{aligned}X _ { 1 } & = \text { engine power } \\X _ { 2 } & = 1 \text { if } 4 \text { cylinders, } 0 \text { if } 6 \text { cylinders } \\Y & = \text { economy expressed as kilometres. }\end{aligned}\end{array}$
-Referring to Instruction 13.41,the fitted model for predicting economy for 4-cylinder cars is ______.

A) 60 - 0.15X₁
B) 40 - 0.10X₁
C) 40 - 0.05X₁
D) 60 - 0.10X₁