7. short-run cost function This is a continuation of problem 6 above. Ralph’s short-run cost curve is given by CSR(q; P) = 1, 200 + 860q − 45q2 + 1.2q3.

(a) Determine Ralph’s fixed, total variable and average variable cost.

(b) Determine Ralph’s short-run total cost, average cost, marginal cost and incremental cost for each integer value of q between 0 and 30. (Again, let incremental cost be the cost of one additional unit.)

(c) Plot and interpret Ralph’s long-run and short-run average cost.

(d) Plot and interpret Ralph’s long-run and short-run marginal cost.