Suppose x = −200p + 12,000 units of a particular commodity are sold each month when the market price is p dollars per unit. The total monthly consumer expenditure E is the total amount of money spent by consumers during each month.

a. Express the total monthly consumer expenditure E as a function of the unit price p, and sketch the graph of E(p).

b. Discuss the economic significance of the p intercepts of the expenditure function E(p).

c. Use the graph in part (a) to determine the market price that generates the greatest total monthly consumer expenditure.