科目：经济学原理与实习一 教授：骆明庆 试别：93学年度上学期期中考 (附解答) 时间：2004.11.22 ---------------------------------------------------------------------- 请在答案卷上清楚地标明题号 一、选择题，回答正确选项即可，不需说明，每题3分，共30分 1. Metro North Railway is trying to decide whether or not to run an additional train into New York City from New Heaven at 8:15 a.m. The total cost of running trains between 8:00 a.m. and 9:00 a.m. is $45,000 and the expected revenues on any given day are $100,000 during this time period. The cost of running the additional train is $4,000 and it is expected that revenues will rise to $104,500. Metro North should (a) run the train because the total revenues are greater than the total costs. (b) not run the train because the total costs are already too high. (c) run the train because the marginal cost is less than the marginal revenue. (d) not run the train because the marginal cost is greater than the marginal revenue. 2. In the marketplace, John voluntarily sells his last two loaves of bread to Mary for $2. We can infer that this will benefit (a) both John and Mary. (b) Mary, but not John, since these are John's last two loaves of bread. (c) Mary, while imposing a cost on John equal to the benefit Mary receives. (d) neither John nor Mary. 3. If a drought destroyed half of the U.S. garlic crop at a time when the health benefits of garlic were being well publicized, economists would expect that in the market for garlic (a) quantity exchanged would rise but the change in price is uncertain without further information. (b) price would rise but the change in quantity exchanged is uncertain without further information. (c) both price and quantity exchanged would rise. (d) price would rise and quantity exchanged would fall. 4. If the fines and jail time for dealing illegal drugs were reduced, we would expect (a) an increased demand for illegal drugs. (b) an increased supply of illegal drugs, a lower price, and higher quantity traded. (c) a decreased supply of illegal drugs, a higher price, and lower quantity traded. (d) no change in the market for illegal drugs because buyers and sellers believe they won't get caught. 5. Rent controls typically end up (a) increasing rents received by landlords. (b) raising property values. (c) encouraging landlords to overspend for maintenance. (d) discouraging new housing construction. 6. Suppose demand for electricity is perfectly inelastic. A tax on electricity will be (a) split between producers and consumers in equal shares. (b) paid only by producers. (c) paid only by consumers. (d) split between producers and consumers in unequal shares. 7. Many U.S. producers complain about limited access to the Japanese market. They say that they cannot export to Japan because Japanese import restrictions are so severe. Who gains? Who loses? (a) Everyone loses. (b) Japanese producers gain, U.S. producers and Japanese consumers lose. (c) Japanese producers and consumers gain, U.S. producers and consumers lose. (d) Japanese consumers and U.S. consumers gain, Japanese producers lose. 8. A dentist shared an office building with a radio station. The electrical current from the dentist's drill causes static in the radio broadcast, causing the radio station to lose $10,000 in discounted future profits. The radio station could put up a shield at a cost of $30,000; the dentist could buy a new drill that causes less interference for $6,000. Either would restore the radio station's lost profits. What is the economically efficient outcome? (a) The radio station puts up a shield, which it pays for. (b) The radio station puts up a shield, which the dentist pays for. (c) The radio station does not put up a shield and the dentist does not buy a new drill. (d) The dentist gets a new drill and it does not matter who pays for it. 9. The commercial value of ivory is a threat to the elephant, but the commercial value of beef is a guardian of the cow. This is because (a) the cow is raised in developed economies while the elephant lives primarily in less-developed nations. (b) cows are private goods while elephants tend to roam without owners. (c) cows and elephants are public good, but ivory is nonrival. (d) ivory is nonrival and nonexclusive but beef is rival and exclusive. 10. A tax that is higher for men then for women violates the criterion of (a) diagonal equity. (b) linear equity. (c) vertical equity. (d) horizontal equity. 二、非选择题，共70分。答题时请务必简洁，并适当说明你的想法。 1. (25分) 简答下列问题。 (a) (5分) 在一个生意兴隆的餐厅里，「二手烟」和「哭闹的小孩」有何相似之处？ (b) (5分) 「再见了，可鲁」是一部描写导盲犬的温馨电影，卖座相当好的结果，将使得 　　拉不拉多犬(可鲁的品种)和体型娇小的吉娃娃犬，其幼犬在宠物市场上的价格分别 如何变化？ (c) (5分) 就政府的角色而言，「流浪教师」的现象和「最低工资」(minimum wage)有何 相似之处？ (d) (5分) 请由是否为excludable和是否为rival的角度，判断「全民健保」属於何种 　　goods？这种goods通常有何问题？ (e) (5分) 几乎所有研究都显示，我国学生升大学与否，和学生的家庭背景，如父母教育 　　程度或家庭所得都成正相关。另一方面，在「低学费」政策之下，公立大学的学费之 　　所以便宜，并不是大学教育的成本低廉，而是政府高度补贴的结果。请评论以下叙述 　　「大学教育有正的外部性，因此政府应该高度补贴公立大学生的学费。」 2. (15分) 阿豪对光泉牛奶的需求表如下。 ----------------- 价格 需求量 ----------------- 5 5 10 4 15 3 20 2 25 1 ----------------- (a) (5分) 当牛奶价格为每瓶20元时，阿豪的消费量为何？此时他共花了多少钱喝牛奶？ (b) (5分) 承上题，若超市以3瓶54元进行促销活动，在仍然可以用每瓶20元的价格购买的 情况之下，阿豪会以54元购买3瓶吗？为什麽？ 　　(题示:由消费者剩余的角度考虑此问题。) (c) (5分) 承(a)，若超市招募会员，只要付入会费8元，就能够用每瓶15元的价格购买牛 　　奶，请问阿豪会加入会员吗？为什麽？ 3. (15分) Suppose that a market is described by the following supply and demand equations: Qs = 2P Qd = 300-P (a) (2分) Solve for the equilibrium price and the equilibrium quantity. (b) (3分) Suppose that a tax T = 60 is placed on buyers, so the new demand equation is Qd = 300-(P+T) = 300-(P+60). Solve for the new equilibrium. What happens to the price received by sellers, the price paid by buyers, and the quantity sold? (c) (4分) From (b), caculate the tax revenue and deadweight loss of the tax? (d) (3分) Instead of placing the tax on buyers, suppose a tax T = 60 is placed on sellers, what is the new supply equation? (Hint:You don't need to answer this part correctly to solve part (e).) (e) (3分) From (d), solve the new equilibrium, what is the price received by sellers, the price paid by buyers, and the quantity sold? 4. (15分) 假设T国之汽车供给来源包括国产车及进口车两种，国产车的供给函数为 Qs = P 国外厂商则愿意在以30元的价格供给任何数量的汽车。此外，汽车的需求函数为 　　　　　　　　　Qd = 100-P (a) (3分) 请画出汽车市场的总供给线。 (b) (3分) 计算均衡时之价格以及进口数量。 (c) (3分) 假设政府为了保护国内汽车产业，决定对进口车课以每辆10元之关税，请问均 　　衡时的价格与进口数量变成多少？ (d) (3分) 承(c)，这10元的关税有多少转嫁给消费者？ (e) (3分) 假设政府放弃关税而改采取进口配额，并限制最多只能有20辆车从国外进口， 　　请问此时均衡价格为何？ ================================================================== 经济学原理一 期中考解答 2004.11.22 一、选择题 1.c 2.a 3.b 4.b 5.d 6.c 7.b 8.d 9.b 10.d 二、非选择题 1a 两者都产生负的外部性。 1b 电影的热卖，造成对拉不拉多犬的需求增加，价格提高。至於属於替代品的吉娃娃犬　 则需求减少，价格下降。 1c 两者都是因为政府订定一个高於市场均衡的价格，使得供过於求。「流浪教师」是政府 在中小学教师的劳动市场上，给予老师明显高於其他行业的待遇，使得想成为老师的人数 ，远多於教师的职缺。「最低工资」则是政府要求雇主支付高於市场均衡水准的工资造成 劳动供给大於劳动需求。 1d 「全民健保」投保者皆可使用医疗资源，但个人的使用会排挤他人的医疗资源，因此 「全民健保」不是excludable，但是rival。所以，「全民健保」是一种common resources ，通常会有被过度使用的问题。 1e 虽然许多人同意「教育有外部性」的说法，但是文献上并没有足够的证据证明大学教育 真的有外部性。即使大学教育真的有「正的外部性」，这只说明了大学生总数较「社会最 适」的大学生数目为低，应该有更多的人读大学。因此，学费补贴的对象应该是处於「读 与不读」或是录取边缘的学生，而不是考试分数较高，家庭背景较好的公立大学学生。对 於国立大学的学生而言，由於家庭环境较好，即使不补贴学费，也不会影响他们就读大学 的决策。因此，对公立大学高度补贴的所谓「低学费政策」，是没有道理的。 2a 2瓶，40元。 2b 本题的作法是比较(1)每瓶20元买两瓶 (2)54元买3瓶，这两种情况的消费者剩余，阿豪 将选择消费者剩余较大的选项。 　 (1)价格为每瓶20元时，阿豪会花40元买2瓶，但他对这2瓶牛奶的愿付价格为25+20=45 元。因此，消费者剩余为5元。(2)在促销活动下，特价品3瓶的价格为54元，这3瓶牛奶对 阿豪的价值为25+20+15=60元，此时消费者剩余为60-54=6元，大於单价20元买2瓶时的消费 者剩余。因此，阿豪会以54元买3瓶。 2c 同上，这里要比较的是(1)每瓶20元买2瓶和(2)入会费8元，每瓶15元，两种情况下的消 费者剩余。 　 价格15元时，由需求表知阿豪会花45元买3瓶，加上入会费，阿豪共花了8+45=53元，阿 豪对3瓶牛奶的愿付价格是60元，消费者剩余为7元。比以20元单买2瓶时的消费者剩余-5元 多，因此阿豪会加入会员。 3a P* = 100 , Q* = 200 . 3b Let Qs = 2P = Qd = 300-(P+60), → Q* = 160. The quantity sold is 160, price received by sellers is 80, and the price paid by the buyers is 140. 3c Tax revenue is T x Q = 60 x 160 = 9600. Deadweight loss is 1/2 x T x ΔQ = 1/2 x 60 x (200-160) = 1200. 3d From the usual demand-supply graph where we put price in the vertical axis and quantity in the horizontal axis, the supply equation is P = 1/2Q. Since placing a tax of T on sellers will shift the supply curve upward by T, the new supply equation is P = T + 1/2 Qs. Therefore, the new supply equation is Qs = 2(P-T) = 2P-120 3e Since it is known that whether a tax is placed on buyers or is placed on sellers does not affect the tax incidence. The price received by sellers, the price paid by buyers, and the quantity sold are the same as the ansewers in (b) We can check this result. Since the new supply function is Qs = 2P-120, and the demand function is Qd = 300-P. Let 2P-120 = 300-P, the price buyers paid is 140. The quantity sold is 2x140-120 = 160, and the price sellers received is 140-60 = 80. 4a 汽车的总供给线为国内厂商与国外厂商供给线的水平加总。本题要注意的是国外厂商的 供给线是一价格为30元的水平线，国内厂商因此不会在价格高於30元以上时生产，总供给 线为如下的一个拗折供给线。 　 当价格低於30时，供给线为Qs = P，当价格等於30时，供给线为一水平线，此时供给弹 性无限大。 4b 此题可直接由供给线与需求现的交点看出，均衡价格为30元。另一个思考的方式是，首 先确认均衡价格绝不会高於30元，因为国外厂商愿意以30元之价格提供任何数量。其次， 当价格低於30元时，国外供给量为零，国内供给量最多为30辆，但此时需求量至少70辆， 所以 P < 30 不会是均衡价格。因此均衡价格必然是30元，进口数量为需求量与国内供给 量之差，70 - 30 = 40 辆。 4c 进口车课以每辆10元的关税之後，进口车的价格变为40元。同上题的推理，若价格低於 40元，进口量为0，国内供给量最多为40辆，但此时需求至少60辆，必须赖进口以满足国内 需求。因此，均衡价格为40元，进口数量为60-40 = 20。 4d 关税使价格上涨10元，10元的关税完全转嫁给消费者，因此此时供给弹性为无限大。 4e 如果没有进口车，国内价格必须高达50元(Qs = P = Qd = 100-P)才能使市场达於均衡 。但在价格往50元调整的过程中，外国车可以用30元的价格进口，由(b)已知，没有进口配 额时，价格为30元，进口数量需为40辆才能达於均衡。因此，在进口配额只有20量的情况 下，价格还会继续上涨，直到需求量与国内供给之差等於20辆时，此时价格为40元，国内 供给量为40辆，需求量为60辆。 　 本题的进口配额，恰与(c)中课徵关税时的进口数量相同，使得采取「10元关税」和 「进口配额20辆」的政策效果完全相同。 --

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