Use the following information from a multiple regression analysis:

n = 20 b1 = 4 b2 = 3 Sb1 = 1.2 Sb2 = 0.8

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

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

iii. 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. Explain.