曼昆微观经济学chapter13讲义资料

《曼昆—微观经济学》重点总结第1篇导言经济学家研究：人们如何作出决策；人们如何相互交易；影响整体经济的力量和趋势。

效率是指经济蛋糕的大小，而平等如此是指如何分割这块蛋糕。

理性人通常通过比拟边际利益与边际本钱来做出决策。

当且仅当一种行为的边际利益＞边际本钱时，一个理性决策者才会采取这种行动。

在经济学中，激励起着中心作用。

价格是“看不见的手〞用来指引经济活动的工具。

产权包括所有权，使用权，处置权，收益权。

市场失灵的原因：垄断；信息不对称；外部性；市场势力。

生产率取决于设备，劳动者的技能以与可用的技术。

·经济学十大原理人们如何做出决策1、人们面临权衡取舍2、某种东西的本钱是为了得到它所放弃的东西3、理性人考虑边际量4、人们会对激励做出反响人们如何相互交易5、贸易可以使每个人的状况都变得更好6、市场通常是组织经济活动的一种好方法7、政府有时可以改善市场结果整体经济如何运行8、一国的生活水平取决于它生产物品与劳务的能力9、当政府发行了过多货币时，物价上升10、社会面临通货膨胀与失业之间的短期权衡取舍第2章像经济学家一样思考·循环流向图：一个说明货币如何通过市场在家庭与企业之间流动的直观经济模型。

P26生产可能性边界：表示在可得到的生产要素与生产技术既定时，一个经济所能生产的产品数量的各种组合的图形。

P28生产可能性边界明确在某一特定时期内生产不同物品之间的权衡取舍，但随着时间的推移，这种权衡取舍可以改变。

·大多数经济学家一致同意的十个主X第3章相互依存性与贸易的好处当每个人专门生产自己有比拟优势的物品时，经济的总产量就增加了。

贸易可以使社会上每个人都获益，因为它使人们可以专门从事他们具有比拟优势的活动。

第2篇市场如何运行第4章供给与需求的市场力量完全竞争市场必须具备两个特征：1.可供销售的物品时完全一样的；2.买者和卖者人数众多，以至于没有任何一个买者或卖者可以影响市场价格。

第13章生产成本跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。

以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。

一、成本1．总收益、总成本和利润总收益（total revenue）：企业从销售其产品中得到的货币量。

总成本（total cost）：企业用于生产的投入品的市场价值。

利润（profit）：企业的总收益减去其总成本。

经济学家通常假设，企业的目标是利润最大化，而且这个假设在大多数情况下都能很好地发挥作用。

2．作为机会成本的成本一种东西的机会成本是指为了得到某种东西所必须放弃的所有东西。

当经济学家提到某个企业的生产成本的时候，它们包括该企业生产其物品与劳务的所有机会成本。

显性成本（explicit costs）：需要企业支出货币的投入成本。

隐性成本（implicit costs）：不需要企业支出货币的投入成本。

经营的总成本是显性成本和隐性成本之和。

经济学家关注于研究企业如何做出生产和定价决策。

由于这些决策既考虑了显性成本又考虑了隐性成本，因此，经济学家在衡量企业的成本时就包括了这两种成本。

与此相反，会计师的工作是记录流入企业和流出企业的货币。

因此，他们衡量显性成本，但往往忽略隐性成本。

3．作为一种机会成本的资本成本几乎每一个企业都有一项重要的隐性成本，那就是已经投资于企业的金融资本的机会成本。

经济学家和会计师以不同的方式来看待和处理成本。

4．经济利润与会计利润由于经济学家和会计师用不同的方法衡量成本，他们也用不同的方法衡量利润。

经济学家衡量企业的经济利润（economic profit），即企业的总收益减去生产所销售物品与劳务的总机会成本（显性的与隐性的）。

第13章生产和成本(一)单项选择题1.总产量曲线的斜率是（ C ）A.总产量B.平均产量C.边际产量D.以上都不是2.当TP下降时，（D ）A.AP L递增B.AP L为零C.MP L为零D.MP L为负3.当AP L为正且递减时，MP L是（ A ）A.递减B.负的C.零D.以上任何一种4.生产过程中某一可变要素的收益递减，这意味着（ B）A.可变要素投入量的增长和产量的增长等幅变化B.产量的增长幅度小于可变要素投入量的增长幅度C. 可变要素投入量的增长幅度小于产量的增长幅度D产量的增长幅度大于可变要素投入量的增长幅度5.某厂商每年从企业的总收入中取出一部分作为自己所提供的生产要素的报酬，这部分资金被视为（B ）。

A.显性成本B.隐性成本C.经济利润 D生产成本6.对应于边际报酬的递增阶段，STC曲线（C ）。

A.以递增的速率上升B. 以递增的速率下降C. 以递减的速率上升 D以递减的速率下降7.短期平均成本曲线成为U形的原因与（C ）有关A.规模报酬B.外部经济与不经济C.要素的边际报酬 D固定成本与可变成本所占比例8.在从原点出发的射线与TC 曲线的相切的产量上，必有（ D）。

A.AC值最小B.AC=MCC.MC曲线处于上升段D.A、B、C、9.如果生产10单位产品的总成本是100美元，第11单位产品的边际成本是21美元，那么（ C）。

A.第11单位产品TVC是21美元B.第10单位产品的边际成本是大于21美元C.11个产品的平均成本是11美元D第12单位产品的平均成本是21美元10.当边际成本小于平均成本时，产量的进一步增加将导致（ B）。

A.平均成本上升B.平均可变成本可能上升也可能下降C.总成本下降D平均可变成本一定是处于减少的状态11.长期平均成本曲线呈U型原因是（A ）。

A.规模报酬的变化所致B.外部经济与不经济所致C.生产要素的边际生产率所致 D固定成本与可变成本所占比重所致12.如果一个厂商的生产是处于规模报酬不变的阶段，则其LAC曲线一定是处于（ C）。

221WHAT’S NEW IN THE SEVENTH EDITION:There are no major changes to this chapter.LEARNING OBJECTIVES:By the end of this chapter, students should understand:what items are included in a firm’s costs of production. the link between a firm’s production process and its total costs.the meaning of average total cost and marginal cost and how they are related. the shape of a typical firm’s cost curves.the relationship between short-run and long-run costs.CONTEXT AND PURPOSE:Chapter 13 is the first chapter in a five-chapter sequence dealing with firm behavior and the organization of industry. It is important that students become comfortable with the material in Chapter 13 because Chapters 14 through 17 are based on the concepts developed in Chapter 13. To be more specific, Chapter 13 develops the cost curves on which firm behavior is based. The remaining chapters in thissection (Chapters 14-17) utilize these cost curves to develop the behavior of firms in a variety of different market structures—competitive, monopolistic, monopolistically competitive, and oligopolistic.The purpose of Chapter 13 is to address the costs of production and develop the firm’s cost curves. These cost curves underlie the firm’s supply curve. In previous chapters, we summarized the firm’s production decisions by starting with the supply curve. While this is suitable for answering manyquestions, it is now necessary to address the costs that underlie the supply curve in order to address the part of economics known as industrial organization —the study of how firms’ decisions about prices and quantities depend on the market conditions they face.KEY POINTS:The goal of firms is to maximize profit, which equals total revenue minus total cost.THE COSTS OF PRODUCTION222 ❖ Chapter 13/The Costs of Production∙When analyzing a firm’s behavior, it is important to include all the opportunity costs of production. Some of the opportunity costs, such as the wages a firm pays its workers, are explicit. Other opportunity costs, such as the wages the firm owner gives up by working at the firm rather than taking another job, are implicit. Economic profit takes both explicit and implicit costs into account, whereas accounting profits consider only explicit costs.∙A firm’s costs reflect its production process. A typical firm’s production function gets flatter as the quantity of an input increases, displaying the property of diminishing marginal product. As a result, a firm’s total-cost curve gets steeper as the quantity produced rises.∙A firm’s total costs can be divided between fixed costs and variable costs. Fixed costs are costs that do not change when the firm alters the quantity of output produced. Variable costs are costs that change when the firm alters the quantity of output produced.∙From a firm’s total cost, two related measures of cost are derived. Average total cost is total cost divided by the quantity of output. Marginal cost is the amount by which total cost rises if output increases by one unit.∙When analyzing firm behavior, it is often useful to graph average total cost and marginal cost. For a typical firm, marginal cost rises with the quantity of output. Average total cost first falls as output increases and then rises as output increases further. The marginal-cost curve always crosses the average-total-cost curve at the minimum of average total cost.∙A firm’s costs often depend on the time horizon considered. In particular, many costs are fixed in the short run but variable in the long run. As a result, when the firm changes its level of production, average total cost may rise more in the short run than in the long run.CHAPTER OUTLINE:I.What Are Costs?A.Total Revenue, Total Cost, and Profit1.The goal of a firm is to maximize profit.Chapter 13/The Costs of Production ❖ 2232.Definition oftotal revenue: the amount a firm receives for the sale of its output.3.Definition of total cost: the market value of the inputs a firm uses in production.4.Definition of profit: total revenue minus total cost.B.Costs as Opportunity Costs1.Principle #2: The cost of something is what you give up to get it.2.The costs of producing an item must include all of the opportunity costs of inputs used inproduction.3.Total opportunity costs include both implicit and explicit costs.a.Definition of explicit costs: input costs that require an outlay of money by thefirm.b.Definition of implicit costs: input costs that do not require an outlay of moneyby the firm.c.The total cost of a business is the sum of explicit costs and implicit costs.d.This is the major way in which accountants and economists differ in analyzing theperformance of a business.e.Accountants focus on explicit costs, while economists examine both explicit and implicitcosts.C.The Cost of Capital as an Opportunity Cost1.The opportunity cost of financial capital is an important cost to include in any analysis of firmperformance.2.Example: Caroline uses $300,000 of her savings to start her firm. It was in a savings accountpaying 5% interest.3.Because Caroline could have earned $15,000 per year on this savings, we must include thisopportunity cost. (Note that an accountant would not count this $15,000 as part of the firm'scosts.)224 ❖ Chapter 13/The Costs of Production4.If Caroline had instead borrowed $200,000 from a bank and used $100,000 from her savings,the opportunity cost would not change if the interest rate stayed the same (according to the economist). But the accountant would now count the $10,000 in interest paid for the bank loan.D.Economic Profit versus Accounting Profit1.Figure 1 highlights the differences in the ways in which economists and accountants calculateprofit.2.Definition of economic profit: total revenue minus total cost, including both explicitand implicit costs .a.Economic profit is what motivates firms to supply goods and services.b.To understand how industries evolve, we need to examine economic profit.3.Definition of accounting profit: total revenue minus total explicit cost .4.If implicit costs are greater than zero, accounting profit will always exceed economic profit.II.Production and CostsA.The Production Function1.Definition of production function: the relationship between quantity of inputs usedto make a good and the quantity of output of that good.2.Example: Caroline's cookie factory. The size of the factory is assumed to be fixed; Carolinecan vary her output (cookies) only by varying the labor used.Number ofWorkersOutputMarginal Productof LaborCost of Factory Cost of WorkersTotal Cost of Inputs 00---$30$0$30150503010402904030205031203030306041402030407051501030508061555306090Chapter 13/The Costs of Production ❖ 2253.Definition of marginal product: the increase in output that arises from an additionalunit of input.a.As the amount of labor used increases, the marginal product of labor falls.b.Definition of diminishing marginal product: the property whereby the marginalproduct of an input declines as the quantity of the input increases.4.We can draw a graph of the firm's production function by plotting the level of labor (x -axis)against the level of output (y -axis).226 ❖ Chapter 13/The Costs of Productiona.The slope of the production function measures marginal product.b.Diminishing marginal product can be seen from the fact that the slope falls as theamount of labor used increases.B.From the Production Function to the Total-Cost Curve1.We can draw a graph of the firm's total cost curve by plotting the level of output (x-axis)against the total cost of producing that output (y-axis).a.The total cost curve gets steeper and steeper as output rises.b.This increase in the slope of the total cost curve is also due to diminishing marginalproduct: As Caroline increases the production of cookies, her kitchen becomesovercrowded, and she needs a lot more labor.Chapter 13/The Costs of Production ❖ 227III.The Various Measures of CostA.Example: Conrad’s Coffee ShopOutputTotal Cost Fixed Cost Variable Cost Average Fixed Cost Average Variable Cost AverageTotalCostMarginal Cost 0 $3.00 $3.00 $0------------1 3.30 3.000.30$3.00$0.30$3.30$0.302 3.80 3.000.80 1.500.40 1.900.503 4.50 3.00 1.50 1.000.50 1.500.704 5.40 3.00 2.400.750.60 1.350.905 6.50 3.00 3.500.600.70 1.30 1.1067.80 3.00 4.800.500.80 1.30 1.3079.30 3.00 6.300.430.901.33 1.50228 ❖ Chapter 13/The Costs of Production811.00 3.008.000.38 1.00 1.38 1.70912.90 3.009.900.33 1.10 1.43 1.901015.003.0012.000.301.201.502.10B.Fixed and Variable Costs1.Definition of fixed costs: costs that do not vary with the quantity of outputproduced.2.Definition ofvariable costs: costs that do vary with the quantity of outputproduced.3.Total cost is equal to fixed cost plus variable cost.C.Average and Marginal Cost1.Definition of average total cost: total cost divided by the quantity of output.2.Definition ofaverage fixed cost: fixed costs divided by the quantity of output.3.Definition of average variable cost: variable costs divided by the quantity of output.4.Definition of marginal cost: the increase in total cost that arises from an extra unitof production.Chapter 13/The Costs of Production ❖ 2295.Average total cost tells us the cost of a typical unit of output and marginal cost tells us thecost of an additional unit of output.D.Cost Curves and Their Shapes1.Rising Marginal Costa.This occurs because of diminishing marginal product.b.At a low level of output, there are few workers and a lot of idle equipment. But as outputincreases, the coffee shop gets crowded and the cost of producing another unit of outputbecomes high.2.U-Shaped Average Total Costa.Average total cost is the sum of average fixed cost and average variable cost.b.AFC declines as output expands and AVC typically increases as output expands. AFC ishigh when output levels are low. As output expands, AFC declines pulling ATC down. Asfixed costs get spread over a large number of units, the effect of AFC on ATC falls andATC begins to rise because of diminishing marginal product.c.Definition of efficient scale: the quantity of output that minimizes average totalcost.3.The Relationship between Marginal Cost and Average Total Costa.Whenever marginal cost is less than average total cost, average total cost is falling.Whenever marginal cost is greater than average total cost, average total cost is rising.b.The marginal-cost curve crosses the average-total-cost curve at minimum average totalcost (the efficient scale).230 ❖ Chapter 13/The Costs of Production4.Typical Cost Curvesa.Marginal cost eventually rises with output.b.The average-total-cost curve is U-shaped.c.Marginal cost crosses average total cost at the minimum of average total cost.IV.Costs in the Short Run and in the Long RunA.The division of total costs into fixed and variable costs will vary from firm to firm.B.Some costs are fixed in the short run, but all are variable in the long run.1.For example, in the long run a firm could choose the size of its factory.2.Once a factory is chosen, the firm must deal with the short-run costs associated with thatplant size.C.The long-run average-total-cost curve lies along the lowest points of the short-run average-total-cost curves because the firm has more flexibility in the long run to deal with changes in production.D.The long-run average-total-cost curve is typically U-shaped, but is much flatter than a typicalshort-run average-total-cost curve.E.The length of time for a firm to get to the long run will depend on the firm involved.F.Economies and Diseconomies of Scale1.Definition of economies of scale: the property whereby long-run average total costfalls as the quantity of output increases.2.Definition of diseconomies of scale: the property whereby long-run average totalcost rises as the quantity of output increases.3.Definition of constant returns to scale: the property whereby long-run average totalcost stays the same as the quantity of output changes.4.FYI: Lessons from a Pin Factorya.In The Wealth of Nations, Adam Smith described how specialization in a pin factoryallowed output to be greater than it would have been if each worker attempted toperform many different tasks.b.The use of specialization allows firms to achieve economies of scale.V.Table 3 provides a summary of all of the various cost definitions used throughout this chapter.SOLUTIONS TO TEXT PROBLEMS:Quick Quizzes1.Farmer McDonald’s opportunity cost is $300, consisting of 10 hours of lessons at $20 an hourthat he could have been earning plus $100 in seeds. His accountant would only count theexplicit cost of the seeds ($100). If McDonald earns $200 from selling the crops, thenMcDonald earns a $100 accounting profit ($200 sales minus $100 cost of seeds) but incursan economic loss of $100 ($200 sales minus $300 opportunity cost).2.Farmer Jones’s production function is shown in Figure 1 and his total-cost curve is shown inFigure 2. The production function becomes flatter as the number of bags of seeds increasesbecause of the diminishing marginal product of seeds. The total-cost curve gets steeper asthe amount of production increases. This feature is also due to the diminishing marginalproduct of seeds, since each additional bag of seeds generates a lower marginal product, andthus, the cost of producing additional bushels of wheat rises.Figure 1Figure 23.The average total cost of producing 5 cars is $250,000/5 = $50,000. Since total cost rosefrom $225,000 to $250,000 when output increased from 4 to 5, the marginal cost of the fifthcar is $25,000.The marginal-cost curve and the average-total-cost curve for a typical firm are shown inFigure 3. They cross at the efficient scale because at low levels of output, marginal cost isbelow average total cost, so average total cost is falling. But after the two curves cross,marginal cost rises above average total cost, and average total cost starts to rise. So thepoint of intersection must be the minimum of average total cost.Figure 34.The long-run average total cost of producing 9 planes is $9 million/9 = $1 million. The long-run average total cost of producing 10 planes is $9.5 million/10 = $0.95 million. Since thelong-run average total cost declines as the number of planes increases, Boeing exhibitseconomies of scale.Questions for Review1.The relationship between a firm's total revenue, profit, and total cost is profit equals totalrevenue minus total costs.2.An accountant would not count the owner’s opportunity cost of alternative employment as anaccounting cost. An example is given in the text in which Caroline runs a cookie business, butshe could instead work as a computer programmer. Because she's working in her cookiefactory, she gives up the opportunity to earn $100 per hour as a computer programmer. Theaccountant ignores this opportunity cost because money does not flow into or out of thefirm. But the cost is relevant to Caroline’s decision to run the cookie factory.3.Marginal product is the increase in output that arises from an additional unit of input.Diminishing marginal product means that the marginal product of an input declines as thequantity of the input increases.4.Figure 4 shows a production function that exhibits diminishing marginal product of labor.Figure 5 shows the associated total-cost curve. The production function is concave becauseof diminishing marginal product, while the total-cost curve is convex for the same reason.Figure 4Figure 55.Total cost consists of the costs of all inputs needed to produce a given quantity of output. Itincludes fixed costs and variable costs. Average total cost is the cost of a typical unit of output and is equal to total cost divided by the quantity produced. Marginal cost is the cost of producing an additional unit of output and is equal to the change in total cost divided by the change in quantity. An additional relation between average total cost and marginal cost is that whenever marginal cost is less than average total cost, average total cost is declining; whenever marginal cost is greater than average total cost, average total cost is rising.Figure 66.Figure 6 shows the marginal-cost curve and the average-total-cost curve for a typical firm.There are three main features of these curves: (1) marginal cost is U-shaped but risessharply as output increases; (2) average total cost is U-shaped; and (3) whenever marginal cost is less than average total cost, average total cost is declining; whenever marginal cost is greater than average total cost, average total cost is rising. Marginal cost is increasing for output greater than a certain quantity because of diminishing returns. The average-total-cost curve is downward-sloping initially because the firm is able to spread out fixed costs over additional units. The average-total-cost curve is increasing beyond some output levelbecause as quantity increases, the demand for important variable inputs increases; therefore, the cost of these inputs increases. The marginal-cost and average-total-cost curves intersect at the minimum of average total cost; that quantity is the efficient scale.7.In the long run, a firm can adjust the factors of production that are fixed in the short run; forexample, it can increase the size of its factory. As a result, the long-run average-total-costcurve has a much flatter U-shape than the short-run average-total-cost curve. In addition,the long-run curve lies along the lower envelope of the short-run curves.8.Economies of scale exist when long-run average total cost decreases as the quantity ofoutput increases, which occurs because of specialization among workers. Diseconomies ofscale exist when long-run average total cost rises as the quantity of output increases, whichoccurs because of the coordination problems inherent in a large organization.Quick Check Multiple Choice1. a2. d3. d4. c5. b6. aProblems and Applications1. a.opportunity cost; b. average total cost; c. fixed cost; d. variable cost; e. total cost; f.marginal cost.2. a.The opportunity cost of something is what must be given up to acquire it.b.The opportunity cost of running the hardware store is $550,000, consisting of $500,000to rent the store and buy the stock and a $50,000 implicit cost, because your aunt wouldquit her job as an accountant to run the store. Because the total opportunity cost of$550,000 exceeds the projected revenue of $510,000, your aunt should not open thestore, as her economic profit would be negative.3. a.The following table shows the marginal product of each hour spent fishing:Hours Fish Fixed Cost Variable Cost Total Cost Marginal Product 00$10$0$10---11010515102181010208324101525642810203045301025352b.Figure 7 graphs the fisherman's production function. The production function becomesflatter as the number of hours spent fishing increases, illustrating diminishing marginalproduct.Figure 7c.The table shows the fixed cost, variable cost, and total cost of fishing. Figure 8 shows the fisherman's total-cost curve. It has an upward slope because catching additional fish takes additional time. The curve is convex because there are diminishing returns to fishing time because each additional hour spent fishing yields fewer additional fish.Figure 84.Here is the completed table:WorkersOutputMarginal Product Total Cost Average Total Cost Marginal Cost00---$200------12020300$15.00$5.00250304008.00 3.3339040500 5.56 2.50412030600 5.00 3.33514020700 5.00 5.00615010800 5.3310.0071555900 5.8120.00a.See the table for marginal product. Marginal product rises at first, then declines becauseof diminishing marginal product.b.See the table for total cost.c.See the table for average total cost. Average total cost is U-shaped. When quantity islow, average total cost declines as quantity rises; when quantity is high, average totalcost rises as quantity rises.d.See the table for marginal cost. Marginal cost is also U-shaped, but rises steeply asoutput increases. This is due to diminishing marginal product.e.When marginal product is rising, marginal cost is falling, and vice versa.f.When marginal cost is less than average total cost, average total cost is falling; the costof the last unit produced pulls the average down. When marginal cost is greater thanaverage total cost, average total cost is rising; the cost of the last unit produced pushes the average up.5.At an output level of 600 players, total cost is $180,000 (600 × $300). The total cost ofproducing 601 players is $180,901. Therefore, you should not accept the offer of $550, because the marginal cost of the 601st player is $901.6. a.The fixed cost is $300, because fixed cost equals total cost minus variable cost. At anoutput of zero, the only costs are fixed cost.b.Quantity TotalCost VariableCostMarginal Cost(using total cost)Marginal Cost(using variable cost)0$300$0------135050$50$50239090404034201203030445015030305490190404065402405050Marginal cost equals the change in total cost for each additional unit of output. It is also equal to the change in variable cost for each additional unit of output. This relationship occurs because total cost equals the sum of variable cost and fixed cost and fixed costdoes not change as the quantity changes. Thus, as quantity increases, the increase intotal cost equals the increase in variable cost.7.The following table illustrates average fixed cost (AFC), average variable cost (AVC), andaverage total cost (ATC) for each quantity. The efficient scale is 4 houses per month,because that minimizes average total cost.Quantity VariableCost FixedCostTotalCostAverageFixed CostAverageVariable CostAverageTotal Cost0$0.00$200.00$200.00---------110.00200.00210.00$200.00$10.00$210.00220.00200.00220.00100.0010.00110.00340.00200.00240.0066.6713.3380.00480.00200.00280.0050.0020.0070.005160.00200.00360.0040.0032.0072.006320.00200.00520.0033.3353.3386.677640.00200.00840.0028.5791.43120.008. a.The lump-sum tax causes an increase in fixed cost. Therefore, as Figure 10 shows, onlyaverage fixed cost and average total cost will be affected.Figure 10b.Refer to Figure 11. Average variable cost, average total cost, and marginal cost will all begreater. Average fixed cost will be unaffected.Figure 119. a.The following table shows average variable cost (AVC), average total cost (ATC), andmarginal cost (MC) for each quantity.Quantity VariableCost TotalCostAverageVariable CostAverageTotal CostMarginalCost0$0.00$30.00---------110.0040.00$10.00$40.00$10.00225.0055.0012.5027.5015.00345.0075.0015.0025.0020.00470.00100.0017.5025.0025.005100.00130.0020.0026.0030.006135.00165.0022.5027.5035.00b.Figure 12 shows the three curves. The marginal-cost curve is below the average-total-cost curve when output is less than four and average total cost is declining. Themarginal-cost curve is above the average-total-cost curve when output is above four and average total cost is rising. The marginal-cost curve lies above the average-variable-cost curve.Figure 1210.The following table shows quantity (Q), total cost (TC), and average total cost (ATC) for thethree firms:Firm A Firm B Firm CQuantity TC ATC TC ATC TC ATC1$60.00$60.00$11.00$11.00$21.00$21.00270.0035.0024.0012.0034.0017.00380.0026.6739.0013.0049.0016.33490.0022.5056.0014.0066.0016.505100.0020.0075.0015.0085.0017.006110.0018.3396.0016.00106.0017.677120.0017.14119.0017.00129.0018.43Firm A has economies of scale because average total cost declines as output increases. Firm B has diseconomies of scale because average total cost rises as output rises. Firm C has economies of scale from one to three units of output and diseconomies of scale for levels of output beyond three units.。