The following data represent a company's yearly sales volume and its advertising expenditure over a period of 8 years. (Y) Sales in (X) Advertising Millions of Dollars in ($10,000) 15 32 16 33 18 35 34 36 17 16 (a) Develop a scatter diagram of sales versus advertising and explain what it shows regarding the relationship between sales and advertising. (b) Use the method of least squares to compute an estimated regression line between sales and advertising by computing bo and bi. (c) If the company's advertising expenditure is $400,000, what are the predicted sales? Give the answer in dollars. (d) What does the slope of the estimated regression line indicate?