6. long-run cost function Ralph’s firm produces a single product. Its long-run cost function is given by C(q; P) = 900q − 40q2 + q3.

(a) Determine Ralph’s total cost, average cost, marginal cost and incremental cost for each integer value of q between 0 and 30.

(Let incremental cost be the cost of one additional unit.)

(b) In a perfectly competitive market, what market price would you expect, and what output would you expect Ralph to produce?

(Hint: under perfectly competitive markets the firm’s profit will be precisely zero).