A manager of a product sales group believes the number of sales made by an employee (Y) depends on how many years that employee has been with the company (X1) and how he/she scored on a business aptitude test (X2). She decides to perform a multiple linear regression to test this belief and use the resulting information for predicting sales. A random sample of 8 employees provides the following data: Employee Y X1 X2

1 100 10 7

2 90 3 10

3 80 8 9

4 70 5 4

5 60 5 8

6 50 7 5

7 40 1 4

8 30 1 1

a. What is the adjusted r2 for this model?

b. What is the value for the three regression coefficients, b0, b1, and b2?

c. For each coefficient, determine whether it is significant at the 95% confidence level? Explain.

d. Using the regression model as estimated, if an employee who had been with the company 5 years scored a 9 on the aptitude test, what does the model predict for his or her expected sales?

e. Prepare a residuals plot against the two independent variables and comment on your interpretation of the results.