7. Short-run equilibrium of industry and firm under perfect competition O (a) Industry P Q (millions) Q e O £ (b) Firm Q (thousands) S D P e MC AR D = AR = MR AC AC
12. Deriving the short-run supply curve O O (a) Industry P £ Q (millions) (b) Firm D 1 = MR 1 D 2 = MR 2 D 3 = MR 3 Q (thousands) = S P 1 S D 1 MC P 2 D 2 P 3 D 3 a b c
14. Deriving the industry short-run supply curve O O (a) Industry P £ P 1 Q (millions) S D 1 (b) Firm D 1 = MR 1 S a P 2 D 2 = MR 2 D 2 b P 3 D 3 = MR 3 D 3 c Q (thousands)
16. Long-run equilibrium under perfect competition O O (a) Industry P £ Q (millions) (b) Firm Q L Q (thousands) New firms enter Supernormal profits Profits return to normal S 1 D LRAC P L P 1 S e AR 1 D 1 AR L D L
17. Long-run equilibrium of the firm under perfect competition £ Q O (SR)AC (SR)MC LRAC AR = MR D L LRAC = (SR)AC = (SR)MC = MR = AR
19. (a) Constant industry costs P Q O Various long-run industry supply curves under perfect competition S 1 D 1 Long-run S S 2 D 2 a b c
20. (b) Increasing industry costs: external diseconomies of scale P Q O S 1 D 1 a Various long-run industry supply curves under perfect competition Long-run S S 2 D 2 b c
21. P Q O S 1 D 1 a Various long-run industry supply curves under perfect competition (c) Decreasing industry costs: external economies of scale Long-run S S 2 D 2 b c
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