Question: Regression is a technique that economists and businesspeople rely on heavily. Think about the relationship between advertising expenditures and sales. Use the data in the accompanying table, which are based on national statistics.

a. Find r

b. Write the regression equation.

c. Plot the regression line on the scatterplot.

d. Predict sales for an advertising expenditure of $10,000.

e. Explain whether any confidence at all can be put in the prediction you made.

Advertising, X                   Sales, Y
($ thousands)               ($ thousands)

3                                       70

4                                      120

3                                      110

5                                      100

6                                      140

5                                      120

4                                      100