Santiago Delgado owns a copier store. He leases two copy machines for which he pays $20 each per day. He cannot increase the number of machines he leases without giving the office machine company six weeks' notice. He can hire as many workers as he wants, at a cost of $40 per day per worker. These are the only two inputs he uses to produce copies.
a. Fill in the remaining columns in the following table.
b. Draw the average total cost curve and marginal cost curve for Santiago's store. Do these curves have the expected shape? Briefly explain.

Quantity of Quantity of Workers per Day Cost Average Total Copies Fixed Variable Total Cost Marginal Cost Cost Cost 1 600 2 1,100 1,500 4 1,800 2,000 2,100 3.