IGCSE AQA Economics: Worked Examples Explained | IGCSE AQA 经济：典型例题详解

📚 IGCSE AQA Economics: Worked Examples Explained | IGCSE AQA 经济：典型例题详解

Preparing for the AQA IGCSE Economics exam requires more than memorising definitions; you need to apply concepts to novel scenarios. This revision article presents a collection of typical worked examples, illustrating how to break down questions, construct logical chains of reasoning, and use diagrams and calculations effectively. Each example reflects the style commonly found in Paper 1 and Paper 2, covering micro- and macroeconomics. Use these model answers to sharpen your exam technique and understand exactly what examiners expect.

备战 AQA IGCSE 经济考试不能只靠背诵定义，你需要将概念运用到新情境中。本文汇集了一系列典型例题，展示如何拆解题目、构建逻辑推理链，并有效运用图表与计算。每个例子对应试卷一和试卷二的常见题型，涵盖微观与宏观经济。利用这些示范答案，你可以磨练应试技巧，确切了解阅卷官的评分要求。

1. Opportunity Cost and Production Possibility Frontier | 机会成本与生产可能性边界

Question: An economy produces only two goods, Food (F) and Clothing (C). The table shows possible output combinations when all resources are used efficiently. Combination A: 0 Food, 500 Clothing; B: 100 Food, 480 Clothing; C: 200 Food, 420 Clothing; D: 300 Food, 300 Clothing; E: 400 Food, 100 Clothing; F: 500 Food, 0 Clothing. (a) Calculate the opportunity cost of producing the first 100 units of Food. (b) Explain why the opportunity cost changes as more Food is produced.

题目：一个经济体只生产食品(F)和衣服(C)两种产品。下表列出了所有资源被有效利用时的可能产出组合。组合A：0 食品，500 衣服；B：100 食品，480 衣服；C：200 食品，420 衣服；D：300 食品，300 衣服；E：400 食品，100 衣服；F：500 食品，0 衣服。(a) 计算生产最初100单位食品的机会成本。(b) 解释为何随着食品产量增加，机会成本会变化。

To find the opportunity cost of the first 100 units of Food, we move from combination A (0F, 500C) to B (100F, 480C). The gain is 100 Food, and the sacrifice is 500 – 480 = 20 Clothing. Therefore, the opportunity cost = 20 Clothing. This means producing 100 Food requires giving up 20 Clothing.

要计算最初100单位食品的机会成本，我们从组合A (0F, 500C) 移到组合B (100F, 480C)。增加的产量是100食品，而牺牲的是500 – 480 = 20衣服。因此机会成本 = 20衣服。这意味着生产100食品需要放弃20衣服。

When we produce further increments of Food, the amount of Clothing given up rises. Moving from B to C (gain 100F): Clothing falls from 480 to 420, a loss of 60C. The opportunity cost has increased from 20 to 60. This occurs because resources are not equally suited to producing both goods. Initially, resources better suited for Food may be idle, so the trade-off is small. As more Food is produced, resources that are more specialised in Clothing must be transferred, leading to a larger sacrifice. This explains the concave (bowed-out) shape of the PPF, reflecting the law of increasing opportunity cost.

当我们继续增加食品产量时，放弃的衣服数量上升。从B移到C（增加100F）：衣服从480降至420，损失60C。机会成本从20增加到60。这是因为资源并非同等适合生产两种产品。最初，更适于产食品的资源可能闲置，因此交换很小。随着食品产量增加，必须转移更专精于衣服的资源，导致牺牲变大。这就解释了生产可能性边界的凹向原点形状，体现了机会成本递增规律。

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2. Shifts in Demand and Supply | 需求与供给的移动

Question: The market for electric bicycles (e-bikes) is in equilibrium. Analyse the effect on equilibrium price and quantity when two changes occur simultaneously: (i) a government subsidy for e-bike manufacturers, and (ii) an increase in the price of petrol, which makes driving cars more expensive. Use a diagram in your explanation.

题目：电动自行车（e-bike）市场最初处于均衡。分析同时发生以下两项变化对均衡价格和数量的影响：(i) 政府给予电动自行车制造商补贴，(ii) 汽油价格上涨，使开车出行更贵。运用图示进行解释。

A subsidy reduces firms’ costs of production, shifting the supply curve to the right (S to S1). At the same time, e-bikes are a substitute for car travel; as petrol becomes dearer, consumers switch to e-bikes, increasing demand. Thus the demand curve shifts right (D to D1). Both shifts push equilibrium quantity up, so quantity definitely rises. The effect on price is ambiguous: the supply shift tends to lower price, while the demand shift tends to raise price. Without knowing the relative magnitudes, the final price could increase, decrease or stay the same.

补贴降低了企业的生产成本，使供给曲线右移（S 到 S1）。同时，电动自行车是汽车出行的替代品；汽油变贵，消费者转向电动自行车，需求增加。因此需求曲线右移（D 到 D1）。两个移动都推动均衡数量上升，所以数量确定增加。对价格的影响则不确定：供给移动倾向于降低价格，而需求移动倾向于抬高价格。在不知道相对幅度的情况下，最终价格可能上升、下降或不变。

If the demand shift is larger, price rises; if the supply shift dominates, price falls. A typical diagram would show Q1 clearly to the right of Qe, while P1 could be above, below or equal to Pe. Examiners expect you to state the ambiguous price outcome explicitly and support it with a well-labelled supply-and-demand diagram showing two alternative equilibria.

如果需求移动幅度更大，价格上升；如果供给移动占主导，价格下降。典型的图示会清楚地显示 Q1 在 Qe 右侧，而 P1 可能高于、低于或等于 Pe。阅卷官期望你明确说出价格结果不确定，并用标注清晰的供求图展示两种可能的均衡。

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3. Calculating Price Elasticity of Demand | 计算需求价格弹性

Question: A cinema reduces its ticket price from £10 to £8. Weekly ticket sales rise from 500 to 650. (a) Calculate the price elasticity of demand (PED) using the midpoint (arc) method. (b) Interpret the result and advise the cinema on total revenue.

题目：一家电影院将票价从10英镑降至8英镑。每周售票量从500张升至650张。(a) 使用中点（弧）法计算需求价格弹性（PED）。(b) 解释结果，并就总收入向电影院提出建议。

PED = (%change in Qd) ÷ (%change in P)

Using the midpoint formula: ΔQ = 650 – 500 = 150, average Q = (500+650)/2 = 575. ΔP = 8 – 10 = -2, average P = (10+8)/2 = 9. %ΔQd = (150/575) × 100 ≈ 26.09%. %ΔP = (-2/9) × 100 ≈ -22.22%. Thus PED = 26.09% ÷ 22.22% = 1.17 (ignoring the negative sign, as we use absolute value). The demand is price elastic (PED > 1).

使用中点公式：ΔQ = 650 – 500 = 150，平均 Q = (500+650)/2 = 575。ΔP = 8 – 10 = -2，平均 P = (10+8)/2 = 9。%ΔQd = (150/575) × 100 ≈ 26.09%。%ΔP = (-2/9) × 100 ≈ -22.22%。因此 PED = 26.09% ÷ 22.22% = 1.17（忽略负号，取绝对值）。该需求富有价格弹性 (PED > 1)。

Because demand is elastic, the percentage increase in quantity demanded (26.09%) outweighs the percentage fall in price (22.22%), so total revenue will rise. Original revenue = £10 × 500 = £5,000. New revenue = £8 × 650 = £5,200. Revenue increases by £200. The cinema should keep the lower price, as long as demand remains elastic and costs are covered.

由于需求富有弹性，需求量增加的百分比（26.09%）大于价格下降的百分比（22.22%），因此总收入将增加。原收入 = 10 × 500 = 5,000 英镑。新收入 = 8 × 650 = 5,200 英镑。收入增加200英镑。电影院应维持低价，只要需求仍保持弹性且成本得到覆盖。

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4. Market Failure: Negative Externalities | 市场失灵：负外部性

Question: Explain why the consumption of cigarettes leads to market failure. Illustrate your answer with a diagram showing the divergence between private and social costs. Suggest one government policy to correct this failure and evaluate its likely effectiveness.

题目：解释为何香烟消费会导致市场失灵。用图示说明私人成本与社会成本的差异，并提出一种政府纠正此失灵的政策，评估其可能的效果。

Cigarette consumption generates negative externalities: the smoker enjoys private benefits but imposes costs on third parties, such as passive smoking health risks and increased public healthcare costs. The free market equates private marginal benefit (PMB) with private marginal cost (PMC), leading to a quantity Qm. However, the social marginal cost (SMC) is higher than PMC because it includes the external cost. The socially optimal quantity is Qs, where PMB = SMC, which is lower than Qm. Thus the market overallocates resources to cigarette production, resulting in welfare loss (deadweight loss triangle).

香烟消费产生负外部性：吸烟者享有私人收益，但给第三方带来成本，如被动吸烟的健康风险和增加的公共医疗费用。自由市场使私人边际收益(PMB)等于私人边际成本(PMC)，形成数量 Qm。然而社会边际成本(SMC)高于 PMC，因为它包含了外部成本。社会最优数量为 Qs，位于 PMB = SMC 处，低于 Qm。因此市场对香烟生产配置了过多资源，产生福利损失（无谓损失三角形）。

A typical corrective policy is an indirect tax equal to the value of the external cost at Qs. The tax shifts the PMC curve upward towards SMC, reducing consumption to the socially efficient level. It also generates government revenue which could fund healthcare. However, effectiveness depends on the price elasticity of demand: if demand is inelastic due to addiction, quantity may not fall sufficiently, and the tax could be regressive. Complementary measures like health warnings and public education are often needed.

典型的纠正政策是征收等同于 Qs 处外部成本价值的间接税。税收使 PMC 曲线向上移动至 SMC，将消费减少至社会有效率水平。它还能带来政府收入，可用于医疗。但效果取决于需求价格弹性：如果因上瘾需求缺乏弹性，数量可能下降不足，且税收可能具有累退性。通常需要健康警示和公共教育等补充措施。

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5. Labour Market and Minimum Wage | 劳动力市场与最低工资

Question: Using a supply and demand diagram for low-skilled labour, analyse the impact of a minimum wage set above the equilibrium wage. Discuss the likely effects on employment and the earnings of workers.

题目：运用低技能劳动力的供求图，分析设定高于均衡工资的最低工资带来的影响。讨论对就业和工人收入的可能效应。

In a competitive labour market, equilibrium wage We and employment Qe are determined by labour supply and labour demand (demand derived from marginal revenue product). If the government imposes a binding minimum wage Wmin > We, the quantity of labour supplied rises to Qs (more workers willing to work), while quantity demanded falls to Qd (firms hire fewer workers). This creates a surplus of labour — unemployment — equal to Qs – Qd. The number of workers employed falls from Qe to Qd, so there is a contraction of employment.

在竞争性劳动力市场中，均衡工资 We 和就业量 Qe 由劳动供给与需求（需求来自边际收益产品）决定。如果政府设定高于 We 的最低工资 Wmin，劳动供给量上升至 Qs（更多工人愿意工作），而劳动需求量降至 Qd（企业减少雇佣）。这产生了劳动力过剩——失业，等于 Qs – Qd。就业人数从 Qe 降至 Qd，就业出现收缩。

For those who remain employed, earnings per worker rise from We to Wmin. The overall wage bill (earnings of all workers) could rise or fall depending on the elasticity of labour demand. If demand is inelastic, the percentage drop in employment is small, so total earnings increase. If demand is elastic, the reduction in numbers employed outweighs the wage rise, causing total earnings to fall. In low-skilled sectors, demand is often inelastic in the short run, so total earnings might increase, but youth and part-time workers often bear the brunt of job losses.

对于保住工作的人，个人收入从 We 升至 Wmin。整体工资总额（全部工人收入）可能增加或减少，取决于劳动需求弹性。如果需求缺乏弹性，就业下降百分比很小，总收入增加。如果需求富有弹性，雇佣量下降的幅度大过工资上涨的幅度，导致总收入下降。在低技能行业，短期内需求往往缺乏弹性，所以总收入可能增加，但青年和兼职工作者往往首当其冲面临失业。

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6. Fiscal Policy Analysis | 财政政策分析

Question: An economy is experiencing rising unemployment and sluggish growth. The government decides to increase spending on infrastructure and cut income tax. Using an AD/AS diagram, explain the expected impact on real GDP and the price level. Discuss one limitation of this policy.

题目：某经济正经历失业上升和增长乏力。政府决定增加基础设施支出并削减所得税。运用 AD/AS 图解释对实际 GDP 和价格水平的预期影响。讨论该政策的一项局限性。

Both measures are expansionary fiscal policies. Increased infrastructure spending directly boosts aggregate demand (AD shifts right from AD1 to AD2) because G (government expenditure) is a component of AD. Cutting income tax raises households’ disposable income, stimulating consumption (C) and further shifting AD right. In the short run, the economy moves to a higher real GDP (Y2) and a higher general price level (P2), assuming upward-sloping short-run aggregate supply (SRAS). Unemployment should fall as output expands.

这两项措施均属于扩张性财政政策。增加基础设施支出直接拉动总需求（AD 从 AD1 右移至 AD2），因为政府支出 G 是 AD 的组成部分。削减所得税提高家庭可支配收入，刺激消费 (C)，进一步右移 AD。在短期，经济移向更高的实际 GDP (Y2) 和更高的总体价格水平 (P2)，假设短期总供给 (SRAS) 向上倾斜。随着产出扩大，失业应下降。

However, a key limitation is time lags: infrastructure projects take months or years to plan and implement, by which time the economy might already be recovering, risking overheating. Additionally, if the economy is near full employment, the AD increase may be largely inflationary with little real GDP gain. Persistent budget deficits could also crowd out private investment if government borrowing pushes up interest rates.

然而，一个关键局限是时间滞后：基础设施项目需要数月甚至数年规划和实施，届时经济可能已在复苏，带来过热风险。此外，如果经济接近充分就业，AD 的增加可能主要表现为通胀，而实际 GDP 增长有限。持续的预算赤字如果导致政府借贷推高利率，也可能挤出私人投资。

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7. Exchange Rates and the Current Account | 汇率与经常账户

Question: The British pound depreciates by 10% against the euro. Explain how this might affect the UK’s current account balance on the balance of payments, distinguishing between the short run and the long run. Refer to the Marshall-Lerner condition.

题目：英镑对欧元贬值10%。解释这可能如何影响英国国际收支中的经常账户余额，区分短期和长期，并提及马歇尔-勒纳条件。

A depreciation makes UK exports cheaper in euro terms and imports from the euro area more expensive in pounds. In the short run, the volume of trade may not adjust immediately because of existing contracts and consumers’ slow response. The current account balance (X – M) might initially worsen — this is the J-curve effect. Export revenue in sterling may fall before quantities rise, while import spending jumps due to higher prices.

本币贬值使英国出口产品以欧元计价更便宜，而从欧元区进口的产品以英镑计价更贵。短期来看，由于已有合同和消费者反应迟缓，贸易量可能不会立即调整。经常账户余额 (X – M) 最初可能恶化——这就是 J 曲线效应。在数量上升之前，以英镑计价的出口收入可能下降，同时因价格更高，进口支出激增。

In the long run, provided the Marshall-Lerner condition holds (sum of price elasticities of demand for exports and imports > 1), the volume response outweighs the price changes. Export volume rises significantly and import volume falls, improving the current account. If the condition is not met, the depreciation may fail to improve the balance. The UK’s trade is generally estimated to satisfy the condition, so a sustained depreciation should eventually raise net exports (X – M), improving the current account.

长期来看，只要马歇尔-勒纳条件成立（出口与进口需求价格弹性之和 > 1），数量反应将超过价格变化。出口量显著增加，进口量下降，从而改善经常账户。如果该条件不满足，贬值可能无法改善余额。据估计，英国贸易通常满足该条件，因此持续的贬值最终应提高净出口 (X – M)，改善经常账户。

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8. Measuring Economic Development | 衡量经济发展

Question: Compare the uses and limitations of GDP per capita and the Human Development Index (HDI) as measures of living standards and development. Use real-world examples to support your answer.

题目：比较人均 GDP 和人类发展指数 (HDI) 作为生活水平和发展衡量指标的用途与局限。使用真实世界例子支持你的答案。

GDP per capita measures the average economic output per person and is widely used to gauge material living standards. It is simple, easily comparable across countries and positively correlated with life expectancy and literacy. However, it has well-known flaws: it ignores income inequality, non-market activities like unpaid housework, environmental degradation and the composition of output (e.g. military spending vs. healthcare). A country like Qatar has very high GDP per capita but scores lower on health and education dimensions compared to its income level.

人均 GDP 衡量人均平均经济产出，被广泛用于评估物质生活水平。它简单、便于跨国比较，并与预期寿命和识字率呈正相关。但它有众所周知的缺点：忽视收入不平等、不计报酬的家务等非市场活动、环境退化以及产出构成（如军费开支与医疗保健）。像卡塔尔这样的国家，人均 GDP 很高，但在健康和教育维度得分相对其收入水平偏低。

HDI combines GDP per capita (adjusted for PPP), life expectancy at birth, and education (mean and expected years of schooling). It captures non-income dimensions of development, giving a fuller picture. Nevertheless, HDI still misses inequality within countries (the IHDI adjusts for this), political freedom, and environmental sustainability. For instance, Sri Lanka has a much lower GDP per capita than Saudi Arabia but a comparable HDI due to better health and education outcomes. Using both metrics together provides a more balanced assessment.

HDI 结合了人均 GDP（经购买力平价调整）、出生时预期寿命和教育（平均与预期受教育年限）。它捕捉了发展的非收入维度，提供了更全面的图景。然而，HDI 仍会忽略国家内部的不平等（不平等调整后 HDI 弥补了这点）、政治自由和环境可持续性。例如，斯里兰卡的人均 GDP 远低于沙特阿拉伯，但因较好的健康与教育成果，其 HDI 水平相近。结合使用两个指标，可以得出更平衡的评估。

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Published by TutorHao | Economics Revision Series | aleveler.com

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