Consider the magazine advertising page cost data from Table 12.1.3. a. Which X variable is the least

Question:

Consider the magazine advertising page cost data from Table 12.1.3.
a. Which X variable is the least helpful in explaining page costs? How do you know?
b. Rerun the regression analysis omitting this X variable.
c. Compare the following results without the X variable to the results with the X variable: F test, R2, regression coefficients, t statistics.