Deriving the short-run supply curve Consider the competitive market for halogen lamps. The following graph shows the marginal cost (MC), average total cost (ATC) and average variable cost (AVC) curves for a typical firm in the industry 30 72 64 56 G 43 e 40 C3 32 24 16 0 816 2 32 4 43 56 64 72 QUANTITY (Thousands of lamps)