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1、1。为什么长期需求弹性与短期需求弹性会有不同？考虑两种商品：纸巾和电视机。哪一种是耐用品？你觉得纸巾的短期需求弹性大,还是长期需求弹性大？为什么？电视机的需求弹性又是怎样的呢?长期需求弹性与短期需求弹性的不同是基于人们对价格变化的敏感反映程度和可替代品数量的多少。对于大多数商品,长期需求远比短期需求富有价格弹性，因为人们要需要较长的时间来改变他的消费习惯。纸巾是非耐用品，如果纸巾的价格上升，在短期消费者无法改变使用纸巾的习惯，短期弹性较小，而在长期，纸巾的需求会随着新的替代品的进入而变的更加有弹性.所与之相反，耐用品的更新换代时间较长,当耐用品的价格上涨时,在短期的需求量会随价格的上升而迅速下
2、降，结果长期需求弹性要小于短期需求弹性。2。Explain why an MRS between two goods must equal the ratio of the price of the goods for the consumer to achieve maximum satisfaction。The MRS describes the rate at which the consumer is willing to trade one good for another to maintain the same level of satisfaction. The ratio o
3、f prices describes the tradeoff that the market is willing to make between the same two goods。 The tangency of the indifference curve with the budget line represents the point at which the trade-offs are equal and consumer satisfaction is maximized. If the MRS between two goods is not equal to the r
4、atio of prices， then the consumer could trade one good for another at market prices to obtain higher levels of satisfaction. For example， if the slope of the budget line （the ratio of the prices） is 4 then the consumer can trade 4 units of good 2 for one unit of good 1. If the MRS at the current bun
5、dle is 6, then the consumer is willing to trade 6 units of good 2 for one unit of good 1. Since the two slopes are not equal the consumer is not maximizing her satisfaction. The consumer is willing to trade 6 but only has to trade 4, so she should make the trade. This trading continues until the hig
6、hest level of satisfaction is achieved. As trades are made, the MRS will change and become equal to the price ratio。3.等产量线可能是凸的、线性的或者L形的.各种形状的等产量线代表了什么性质的生产函数？又意味着什么样的边际技术替代率?等产量线是由生产出同一产量的不同投入品组合形成的曲线.凸的等产量线表明边际技术替代率递减，任何一种投入品的生产率都是有限的。如果等产量线是线性的，说明两种投入品之间是完全可替代的，此时边际技术替代率在等产量线上的所有点均为常数.如果等产量线是L型的，
7、此时投入品之间不能进行任何替代，投入品只有按相同比例递增,在L型等产量线的垂直部分和水平部分，投入品的边际产出均为零。4。Assume the marginal cost of production is increasing. Can you determine whether the average variable cost is increasing or decreasing? Explain。Marginal cost can be increasing while average variable cost is either increasing or decreasing.
8、If marginal cost is less （greater) than average variable cost, then each additional unit is adding less (more) to total cost than previous units added to the total cost， which implies that the AVC declines (increases). Therefore， we need to know whether marginal cost is greater than average variable
9、 cost to determine whether the AVC is increasing or decreasing。5。 Why would a firm that incurs losses choose to produce rather than shut down?Losses occur when revenues do not cover total costs。 Revenues could be greater than variable costs, but not total costs， in which case the firm is better off
10、producing in the short run rather than shutting down， even though they are incurring a loss。 The firm should compare the level of loss with no production to the level of loss with positive production， and pick the option that results in the smallest loss。 In the short run， losses will be minimized a
11、s long as the firm covers its variable costs。 In the long run， all costs are variable, and thus, all costs must be covered if the firm is to remain in business。6。Can there be constant returns to scale in an industry with an upward-sloping supply curve？ Explain。Constant returns to scale imply that pr
12、oportional increases in all inputs yield the same proportional increase in output. Proportional increases in inputs can induce higher prices if the supply curves for these inputs are upward sloping. For example, production that uses rare or depleting inputs will see higher costs of production as pro
13、duction increases in scale. Doubling inputs will still yield double output, but because of rising costs, the firm cannot offer increasing amounts of the good without higher prices. Therefore， constant returns to scale does not always imply longrun horizontal supply curves.7。Suppose the government wa
14、nts to limit imports of a certain good。 Is it preferable to use an import quota or a tariff？ Why?Changes in domestic consumer and producer surpluses are the same under import quotas and tariffs. There will be a loss in （domestic) total surplus in either case。 However， with a tariff， the government c
15、an collect revenue equal to the tariff times the quantity of imports and these revenues can be redistributed in the domestic economy to offset the domestic deadweight loss by， for example, reducing taxes. Thus， there is less of a loss to the domestic society as a whole. With the import quota, foreig
16、n producers can capture the difference between the domestic and world price times the quantity of imports。 Therefore， with an import quota, there is a loss to the domestic society as a whole. If the national government is trying to increase welfare, it should use a tariff.8。Why does a tax create a deadweight loss? What determines the size of this loss？A tax creates deadweight loss by artificially increasing price above the free
