Starting with the data fro Problem 6 and the data on the price of a related commodity for the years 1986 to 2005 given below, we estimated the regression for the quantity demanded for a commodity (which we now relable (Q x), on the price of the commodity (which we now relable (Qx), on the price of the commodity (which we now lable Px), consumer income (which we now label Y), and price of the rleated commodity (Pz), and we obtgained the following results.Qx=121.86-9.50Px+ 0.04Y – 2.21P(-5.12) (2.18) (-0.68)R2=0.9633 F=167.33 D-W=2.38(a) Explain why you think we have chosen to include the price of commodity Z in the above regression. (b) Evaluate the above regression results. (P.211)