2-2 One of your firm's suppliers discounts prices for larger quantities. The first 1000 parts are $13 each. The next 2000 are $12 each. All parts in excess of 3000 cost $11 each. What are the average cost and marginal cost per part for the following quantities?

(a) 500

(b) 1500

(c) 2500

(d) 3500