The file P13_67.XLS contains hypothetical starting salaries (in $1000’s) for MBA students directly after graduation. The file also lists their years of experience prior to the MBA program and their class standing in the MBA program (on a 0-100 scale). 

a. Estimate the regression equation with Salary as the response variable and Exper and Class as the explanatory variables. What.does this equation imply? What does the standard error of estimate s, tell you? What about R²? 

b. Repeat part a, but now include the interaction term Exper*Class (the product) in the equation as well as Exper and Class individually. Answer the same questions as in part a. What evidence is there that this extra variable (the interaction variable) is worth including? How do you interpret this regression equation?