黄新飞 《微观经济学》chapter 8 perfect competition.pptVIP

Effect of Increase in Demand on Price Varies in Different Time Periods Long-Run Industry Supply Depends on Cost Conditions 课堂测试 已知完全竞争厂商成本函数TC=0.02Q^2-12Q+2000，产品单价P=20，求厂商利润最大化的产量和利润。 Constant-Cost Case Increasing-Cost Case * 课堂测试 缅因州的龙虾业非常活跃，在每年夏季收获。在一年中的其他时间里，可以在世界的其他地方捕捞到龙虾，但龙虾的价格非常高。缅因州有许多只在夏天营业的路边店出售烹制好的龙虾。请解释为什么对路边店来说只在夏天出售龙虾是最优选择。 * Long Run Equilibrium P=ATC MC ATC q MR P In the long run, a perfectly competitive industry will be in equilibrium where price equals average total cost. At this point, firms will earn normal profits or zero economic profits. * Economic vs. Accounting Profit The real rate of return will be roughly three percentage points above the return you could have earned investing in risk free government bonds. So, after adjusting for risk, any investment yielding you that return would be considered a normal profit or zero economic profits. Note that your profit from an accounting standpoint isn’t zero at all. You’ve simply been fairly compensated for your equity capital – no more and no less. * Long Run Equilibrium In the long run, a perfectly competitive industry will produce where price equals the average total cost curve at its minimum and earn zero economic profits. How does the industry remarkably wind up at this particular point? The answer lies in one of our original assumptions: free entry and exit into the market. * MC ATC 100 q P $50 AS 100,000 P Q AD $50 What will happen to these figures after a report comes out showing that widgets can reduce the incidence of Alzheimer’s disease? * P 50 MR2 60 The Market For Widgets MC ATC 100 q MR1 S 100,000 P Q D2 60 100,000 Q 60 D1 50 * P 50 60 MC ATC MR1 MR2 100 S 100,000 P Q D1 50 D2 60 a) The industry supply curve shifts in. This drive the price back down to $50 and economic profits back to zero. b) This industry supply curve shifts out. This drives the price back down to $50 and economic profits back to zero. c) The industry curve bends into a pret