You are given the following information from a multiple regression analysis:

n = 45, b1 = 7, b2 = 6, Sb1

= 2.5, Sb2

= 1.5

a. Which variable has the largest slope in units of a t statistic?

b. Construct a 95% confidence interval estimate of the population slope β1.

c. At the 0.05 level of significance, determine whether each independent variable makes a significant contribution to the regression model. On the basis of these results, indicate the independent variables to include in this model.