Enter the appropriate value to answer the question or solve the problem. 15. A demand curve is given by 300 P x + 8 ' Find the consumer surplus when the selling price is $20.16. Find the area of the surface obtained by rotating the curve about the y-axis. Inx, ISx52 2 3 TT a. 2 10 b. 3 8 TT C. 3 11 7 d. 2 e. None of these