1、国际经济学AnswersChap02Answers to in-text Questions in Economics (5th ed)Chapter 2Page 31 Assume that there are 200 consumers in the market. Of these, 100 have schedules like Traceys and 100 have schedules like Darrens. What would be the total market demand schedule for potatoes now?Price(pence per kg)To
2、tal market demand(kg) 20 40 60 80100440026001400 800 600 32 1. How much would be demanded at a price of 6p per kilogram? Reading off from the graph: at a price of 6p per kg, total market demand is 600 000 tonnes per month (or a little under). 2. Assuming that demand does not change from month to mon
3、th, plot the annual market demand for potatoes. The amount demanded would be 12 times higher at each price. If the scale of the horizontal axis were unaltered, the curve would shift way out to the right. A simple way of showing the new curve, therefore, would be to compress the scale of the horizont
4、al axis. (If each of the numbers on the axis were multiplied by 12, the curve would remain in physically the same position.) 1. Draw Traceys and Darrens demand curves for potatoes on one diagram. Note that you will use the same vertical scale as in Figure 2.1, but you will need a quite different hor
5、izontal scale. This is shown in Diagram 2.1.Page 32 2. At what price is their demand the same? The two curves cross at a price of 10p per kg and at a demand of 10 kg per month. 3. What explanations could there be for the quite different shapes of their two demand curves? One explanation could be tha
6、t Tracey is quite happy to eat rice, pasta or bread instead of potatoes. Thus when the price of potatoes goes up she switches to these other foods, and switches to potatoes when the price of potatoes comes down. Darren, by contrast, may not see these other foods as close substitutes and thus his dem
7、and for potatoes will be less price sensitive. (See section 2.4 on elasticity.) 33 Do all these six determinants of demand affect both an individuals demand and the market demand for a product? All except the distribution of income. The (national) distribution of income simply affects an individuals
8、 income and thus is not a separate determinant from income. 1. Assume that in Table 2.1 the total market demand for potatoes increases by 20 per cent at each price due, say, to substantial increases in the prices of bread and rice. Plot the old and the new demand curves for potatoes. Is the new curv
9、e parallel to the old one? See Diagram 2.2 below. As you can see, the curves are not parallel. A constant percentage increase in quantity demanded gives a bigger and bigger absolute increase as quantity increases. 2. The price of pork rises and yet it is observed that the sales of pork increase. Doe
10、s this mean that the demand curve for pork is upward sloping? Explain. No not necessarily. For example, the price of substitutes such as beef, chicken or lamb may have risen by a larger amount. In such cases the demand curve for pork will have shifted to the right. Thus although a rise in the price
11、of pork will cause a movement up along this new demand curve, more pork will nevertheless be demanded because pork is now relatively cheaper than the alternatives.Page 34 1. Complete the demand schedule in Table 2:2 up to a price of 50. PQd 5101520253035404550900080007000600050004000300020001000 0 2
12、. What is it about equation (2) that makes the demand curve (a)downward sloping; (b)a straight line? (a) The fact that the 200P term has a negative sign. This means that as P rises, so Qd falls. (b) The fact that there is no P to a power term. The curve thus has a constant slope of 1/200 1. Referrin
13、g to equation (3), if the term a has a value of 50000 and the term b a value of 0.001, construct a demand schedule with respect to total income (Y). Do this for incomes between 100 million and 300 million at 50 million intervals. Y (millions)Qd100150200250300 50 000100 000150 000200 000250 000 2. No
14、w use this schedule to plot a demand curve with respect to income. Comment on its shape. The curve will be an upward-sloping straight line, crossing the horizontal axis at 50 000. It would rise by 100000 units for each 100million rise in national income. (See Diagram 2.3).Page 35 (Box 2.1) From this
15、 equation, calculate what would happen to the demand for lamb if: (a) the price of lamb went up by 10p per kg (at 1985 prices). (b) the price of beef went up by 10p per kg (at 1985 prices). (c) personal disposable income per head went up by 100 per annum (at 1985 prices). (a) The demand would go dow
16、n by 1.12 grams per person per week (i.e. 10 0.112). (b) The demand would go up by 1.25 grams per person per week (i.e. 10 0.125). (c) The demand would go down by 1.98 grams per person per week (i.e. 100 0.0198). (Box 2.1) 1. How does the introduction of the TIME term affect the relationship between
17、 the demand for lamb and (a) the price of beef and (b) personal disposable income per head? (a) The demand for lamb is less sensitive to a change in the price of beef than in the first equation. (b) The demand for lamb is slightly more sensitive to a change in disposable income than in the first equ
18、ation and the relationship is now a positive one: i.e. when income rises, the demand for lamb rises. (Box 2.1) 2. Is lamb a normal good or an inferior good? An inferior good in the first equation and a normal good in the second. In the first equation, as personal disposable income rises so the deman
19、d for lamb falls. In the second equation as personal disposable income rises so the demand for lamb rises. The reason is that, by introducing the TIME term, we are now allowing for the fall in demand for lamb over time as a result of a shift in tastes away from meat. In other words, the second equat
20、ion allows us to take this factor out of account when looking at the effect of a change in the price of lamb on the demand for lamb. (Box 2.1) Use the second equation to estimate the demand for lamb in 1994, 1996 and 2000. In which of these three years was the estimation closest to the actual figure
21、? Explain the divergences in the actual figures from the figures derived from the equation. 1994: Qd = 192.3 (0.530 301.6) + (0.0738 343.0) + (0.0261 8266) (7.352 29) = 192.3 159.85 + 25.31 + 215.74 213.21 = 60.29 (grams per person per week) 1996: Qd = 192.3 (0.530 296.2) + (0.0738 325.6) + (0.0261
22、8607) (7.352 31) = 192.3 156.99 + 24.03 + 224.64 227.91 = 56.07 (grams per person per week) 2000: Qd = 192.3 (0.530 310.7) + (0.0738 320.1) + (0.0261 9604) (7.352 35) = 192.3 164.67 + 23.62 + 250.66 257.32 = 44.59 (grams per person per week) The equation most closely predicted the actual consumption
23、 in 1994: actual consumption (54 grams pppw) was 6 grams pppw less than predicted by the equation. In 1996 and 2000, consumption was approximately 10 grams pppw more than predicted. This can be explained by BSE, which caused a shift in demand from beef to lamb in these later two years. 37 1. How muc
24、h would be supplied at a price of 70p per kilo? About 430 000 tonnes per month. 2. Draw a supply curve for farmer X. Are the axes drawn to the same scale as in Figure 2.4? The supply curve for farmer X will merely plot the relevant two columns from Table 2.3. The vertical axis can be drawn to the sa
25、me scale as in Figure 2.4, but a different scale will have to be used for the horizontal axis (e.g. tonnes rather than thousands of tonnes). 38 1. For what reasons might the supply of potatoes fall? Examples include: The cost of producing potatoes rises. The profitability of alternative crops (e.g.
26、carrots) rises. A poor potato harvest. Farmers expect the price of potatoes to rise (short-run supply falls).Page 38 2. For what reasons might the supply of leather rise? Examples include: The cost of producing leather falls. The profitability of producing alternative products decreases. The price o
27、f beef rises. A long-running industrial dispute involving leather workers is resolved. Producers expect the price of leather to fall (short-run supply increases).39 This question is concerned with the supply of oil for central heating. In each case consider whether there is a movement along the supp
28、ly curve (and in which direction) or a shift in it (left or right). (a) New oil fields start up in production. (b) The demand for central heating rises. (c) The price of gas falls. (d) Oil companies anticipate an upsurge in demand for central-heating oil. (e) The demand for petrol rises. (f) New tec
29、hnology decreases the costs of oil refining. (g) All oil products become more expensive. (a) Shift right. (b) Movement up along (as a result of a rise in price). (c) Movement down along (as a result of a fall in price resulting from a fall in demand as people switch to gas-fire central heating). (d)
30、Shift left (if companies want to conserve their stocks in anticipation of a price rise). (e) Shift right (more of a good in joint supply is produced). (f) Shift right. (g) Movement up along. 1. If P was originally measured in s, what would happen to the value of the d term if P were now measured in
31、pence? It would now have a value of 10. 2. Draw the schedule (table) and graph for equation (8) for prices from 1 to 10. What is it in the equation that determines the slope of the supply curve? PQs12345678910 15002500350045005500650075008500950010500 The graph is an upward sloping straight line crossing the horizontal axis at 500 units. The slope is given by the value of the d term: i.e. the slope is 1/1000 (for every 1 increase in price, quantity s
