Suppose the market demand function is Qd = 8I - 9P1 - 0.5P2 where I is income in $1,000 and P1 is price of a related good.
(a) What is the relation between these two goods?
(b) Calculate the income, cross price, and own price elasticity of demand if I = $40,000, P1 = $10 and P = $15.
(c) At what price is demand unit elastic if I = $40,000 and P1 = $10?