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Tài liệu tham khảo Tài liệu trung cấp môn Kinh tế vi mô bằng tiếng Anh gồm 41 phần giúp sinh viên khoa kinh tế học tốt môn Kinh tế vi mô. Tài liệu này là phần 24 giới thiệu về " Industry supply " | CHAPTER 23 INDUSTRY SUPPLY We have seen how to derive a firm s supply curve from its marginal cost curve. But in a competitive market there will typically be many firms so the supply curve the industry presents to the market will be the sum of the supplies of all the individual firms. In this chapter we will investigate the industry supply curve. 23.1 Short-Run Industry Supply We begin by studying an industry with a fixed number of firms n. We let Si p be the supply curve of firm i so that the industry supply curve or the market supply curve is S p 2 1 which is the sum of the individual supply curves. Geometrically we take the sum of the quantities supplied by each firm at each price which gives us a horizontal sum of supply curves as in Figure 23.1. 402 INDUSTRY SUPPLY Ch. 23 The industry supply curve. The industry supply curve Si S2 is the sum of the individual supply curves Si and S2 . 23.2 Industry Equilibrium in the Short Run In order to find the industry equilibrium we take this market supply curve and find the intersection with the market demand curve. This gives us an equilibrium price p . Given this equilibrium price we can go back to look at the individual firms and examine their output levels and profits. A typical configuration with three firms A B and C is illustrated in Figure 23.2. In this example firm A is operating at a price and output combination that lies on its average cost curve. This means that P ----- y Cross multiplying and rearranging we have py - c y 0. Thus firm A is making zero profits. Firm B is operating at a point where price is greater than average cost p c y y which means it is making a profit in this short-run equilibrium. INDUSTRY EQUILIBRIUM IN THE LONG RUN 403 Short-run equilibrium. An example of a short-run equilibrium with three firms. Firm A is making zero profits firm B is making positive profits and firm C is making negative profits that is making a loss. Firm C is operating where price is less than average cost so it is .
