The Klein Corporation's marketing department, using regression analysis, estimates the firm's demand function, the result being

Q=-104-2.1P + 3.2I+1.5A + 1.6ZR2=0.89

Standard error of estimate=108

where Q is the quantity demanded of the firm's product (in tons), P is the price of the firm's product (in dollars per ton), I is per capita income (in dollars), A is the firm's advertising expenditure (in thousands of dollars), and Z is the price (in dollars) of a competing product. The regression is based on 200 observations.

b. If I=5,000, A = 20, and Z= 1,000, what is the Klein Corporation's

demand curve?

c. If P=500 (and the conditions in part b hold), estimate the quantity

demanded of the Klein Corporation's product.

d. How well does this regression equation fit the data?