8. Short-run equilibrium of industry and firm under perfect competition fig O £ (b) Firm Q (thousands) O (a) Industry P Q (millions) Q e S D P e MC AR D = AR = MR AC AC
9. Short-run shut-down point fig O O (a) Industry P Rs Q (millions) S (b) Firm MC AC Q (thousands) D 2 P 2 AR 2 D 2 = AR 2 = MR 2 AVC
10. Long-run equilibrium under perfect competition fig O O P £ Q (millions) Q L Q (thousands) New firms enter Supernormal profits Profits return to normal (a) Industry (b) Firm S 1 D LRAC P L P 1 S e AR 1 D 1 AR L D L
11.
12. Long-run equilibrium of the firm under perfect competition Rs Q O (SR)AC (SR)MC LRAC AR = MR D L LRAC = (SR)AC = (SR)MC = MR = AR