📚 Case Study Drill for Year 9 AQA Economics | 九年级AQA经济学案例分析实战演练
Welcome to a hands‑on case study session designed especially for Year 9 students following the AQA Economics route. We will work through a realistic business scenario – a small smoothie company called 'FruitFlow' – and use it to sharpen your ability to identify, apply and evaluate key economic ideas. By the end, you will feel ready to tackle any case‑based question with confidence.
欢迎来到这堂专为九年级AQA经济学学生设计的案例分析实战课。我们将围绕一个真实的商业情景——一家名为“FruitFlow”的小型果昔公司——展开分析，并借此强化你识别、应用和评估关键经济概念的能力。完成本课学习后，你将信心满满地应对任何基于案例的问题。
1. Getting to Know the Case: FruitFlow Smoothies | 认识案例：FruitFlow果昔
FruitFlow is a small firm that produces fresh smoothies using strawberries, bananas and yogurt. It sells directly to local cafés and at a weekly farmers’ market. The owner, Mia, has noticed that when she raises prices even a little, customers buy noticeably fewer smoothies. She is also worried because the cost of strawberries has risen sharply after a poor harvest, and a new competitor has just opened a stall nearby.
FruitFlow是一家用草莓、香蕉和酸奶生产新鲜果昔的小企业，产品直接卖给当地咖啡馆，也在每周农贸市场上出售。店主Mia发现，即便只是小幅提价，顾客购买的果昔数量也会明显减少。她还担心，由于收成不佳，草莓成本大幅上涨，而且附近刚开了一个新的竞争摊位。
Your task throughout this article is to put yourself in Mia’s position, using economic tools to understand what is happening and to suggest sensible next steps. Every case study begins with careful reading – underline the facts, note any numbers and look for clues about cause and effect.
你的任务就是站在Mia的角度，运用经济学工具来理解正在发生的变化，并提出合理的应对措施。任何案例分析都从仔细阅读开始——划出事实，记下数字，并寻找因果关系的线索。
2. Scarcity and Choice: The Core Problem | 稀缺性与选择：核心问题
Mia’s situation illustrates the basic economic problem: resources are scarce, but wants are unlimited. Strawberries are no longer plentiful; she must decide how to allocate her limited funds, time and ingredients. Should she use more bananas instead of strawberries? Should she reduce the size of each smoothie? Every decision involves an opportunity cost – the next best alternative forgone.
Mia的处境揭示了基本的经济问题：资源是稀缺的，但人类欲望是无限的。草莓不再充裕，她必须决定如何分配有限的资金、时间和原料。是应该多用香蕉代替草莓？还是缩小每杯果昔的份量？每一个决策都涉及机会成本——即所放弃的次优选择。
- If Mia keeps using the same quantity of strawberries, she will have less profit to spend on advertising. The opportunity cost is the extra customers she might have attracted with that advertising.
- 如果Mia继续使用同样数量的草莓，她用于广告宣传的利润就会减少。机会成本就是她原本可能通过广告吸引到的额外顾客。
- If she replaces some strawberries with banana, the opportunity cost is the taste and quality that loyal customers expect, which might reduce future demand.
- 如果她用香蕉替代部分草莓，机会成本则是老顾客所期望的口感和品质，这可能导致未来需求下降。
Economists call this process ‘thinking at the margin’. Mia should compare the marginal cost of an extra strawberry smoothie with its marginal benefit. Only if the benefit exceeds the cost should she continue with the same recipe.
经济学家将这种思维称为“边际思考”。Mia应当比较多生产一杯草莓果昔的边际成本与边际收益。只有当收益大于成本时，她才应坚持原有配方。
3. Demand: Why Do Customers Buy Less When Price Rises? | 需求：为什么价格上涨后顾客买得更少？
Mia has observed that a small price increase leads to a big fall in the quantity demanded. This suggests the demand for her smoothies is price elastic. In economic terms, when the percentage change in quantity demanded is greater than the percentage change in price, demand is elastic. Elastic demand is common for products that have many close substitutes or are seen as luxuries rather than necessities.
Mia观察到，价格的小幅上涨会导致需求量大幅下降。这表明她的果昔需求是富有价格弹性的。用经济学语言来说，当需求量的百分比变化大于价格的百分比变化时，需求就是富有弹性的。弹性需求常见于存在许多相近替代品，或被看作奢侈品而非必需品的产品。
We can express this using a simple elasticity formula:
Price Elasticity of Demand (PED) = (% Change in Quantity Demanded) ÷ (% Change in Price)
我们可以用一个简单的弹性公式来表示：
需求价格弹性（PED）= （需求量变化百分比）÷ （价格变化百分比）
If Mia’s 10% price rise caused a 25% drop in sales, her PED would be −2.5 (ignoring the minus sign, the value is 2.5, which is greater than 1, confirming elastic demand). This tells her that raising price is likely to lower total revenue, because the loss from selling fewer units outweighs the gain from the higher price.
如果Mia提价10%导致销量下降25%，她的PED值将是−2.5（忽略负号，数值2.5大于1，确认弹性需求）。这告诉她，提价很可能会降低总收入，因为销量减少带来的损失超过了更高单价带来的收益。
Several factors make FruitFlow’s demand elastic: the new competitor’s smoothies are a close substitute, customers can easily switch to bottled juices, and a smoothie is a discretionary purchase, not an essential good. Understanding demand helps Mia see that a price cut might actually boost her total revenue.
有几个因素使FruitFlow的需求富有弹性：新竞争者的果昔是相近的替代品，顾客可以轻易转向瓶装果汁，而果昔是一种非必需品。理解需求有助于Mia认识到，降价反而可能提高她的总收入。
4. Supply: The Strawberry Cost Shock | 供给：草莓成本冲击
Supply is not just about the quantity producers are willing to sell at each price; it also depends on the costs of production. A poor harvest has raised the price of strawberries – a key input. This increases Mia’s production costs, causing the supply curve for her smoothies to shift to the left. At every price level, she is now willing and able to supply fewer smoothies than before.
供给不仅关乎生产者在每一价格下愿意出售的数量，还取决于生产成本。歉收推高了草莓——一种关键投入品——的价格。这使得Mia的生产成本增加，导致她果昔的供给曲线向左移动。在每一价格水平上，她愿意且能够供应的果昔数量都比以前少了。
The supply shift can be shown by comparing two scenarios:
| Price per smoothie (p) | Original quantity supplied per day | New quantity supplied after cost rise |
|---|---|---|
| £2.00 | 80 | 55 |
| £2.50 | 110 | 85 |
| £3.00 | 140 | 110 |
Other supply factors, such as technology and indirect taxes, could also shift supply. Mia could invest in a better blender (improved technology) to increase productivity, partially offsetting the higher fruit costs.
其他供给因素，如技术和间接税，也能使供给发生移动。Mia可以投资一台更好的搅拌机（技术改进）来提高生产率，从而部分抵消水果成本的上升。
5. Market Equilibrium: Finding the New Balance | 市场均衡：寻找新的平衡点
Before the cost shock, FruitFlow’s smoothies were selling at an equilibrium price of £2.50, where quantity demanded matched quantity supplied. With the supply curve shifting left, there is now an imbalance: at the old price, quantity demanded still sits around 110 units per day, but Mia is only willing to supply 85 units. A shortage of 25 smoothies appears.
在成本冲击之前，FruitFlow的果昔以2.50英镑的均衡价格出售，此时需求量等于供给量。随着供给曲线向左移动，现在出现了失衡：在旧价格下，需求量仍约为每天110杯，但Mia只愿意供给85杯。出现了25杯果昔的短缺。
In a free market, this shortage puts upward pressure on price. As the price rises, some consumers drop out (demand contracts), and the higher price encourages Mia to supply a little more (extension of supply). A new, higher equilibrium price will emerge – perhaps around £2.80 – where quantity demanded and supplied meet again, though at a lower quantity than before.
在自由市场中，这种短缺会对价格产生上行压力。随着价格上涨，一些消费者退出市场（需求收缩），而更高的价格会激励Mia略微增加供给（供给扩张）。一个新的、更高的均衡价格将会出现——可能在2.80英镑左右——此时需求量与供给量再次相等，但交易量比以前更低。
It is essential to remember that ‘equilibrium’ does not mean everything is perfect – it is simply a state of balance where there is no tendency for price to change further, given current conditions.
必须记住，“均衡”并不意味着一切都很完美——它只是一种平衡状态，在现有条件下价格没有进一步变动的趋势。
6. The Price Mechanism: Signalling Scarcity | 价格机制：传递稀缺信号
The rising price of strawberries and the shift in the smoothie market are excellent examples of the price mechanism at work. Prices perform three vital functions: they signal changing conditions, they ration scarce resources, and they provide incentives for both producers and consumers to adjust their behaviour.
草莓价格上涨以及果昔市场的变化是价格机制发挥作用的绝佳例子。价格具有三个重要功能：传递不断变化的情况，配给稀缺资源，以及为生产者和消费者调整行为提供激励。
- Signalling: The higher strawberry price tells Mia ‘strawberries are scarcer, find alternatives or use them more carefully’. The higher smoothie price will tell customers ‘this drink uses expensive ingredients’.
- 信号功能： 更高的草莓价格告诉Mia“草莓更稀缺了，寻找替代品或更加节约使用”。更高的果昔价格将告诉顾客“这款饮品使用了昂贵的原料”。
- Rationing: As smoothie price rises, only those who value the drink most highly (and can afford it) will continue to buy. The scarce strawberries are therefore allocated to their most valued use.
- 配给功能： 随着果昔价格上升，只有那些最看重这种饮品（且买得起）的人才继续购买。因此，稀缺的草莓被分配给了评价最高的用途。
- Incentives: Mia has an incentive to find cheaper substitutes or improve efficiency. Consumers have an incentive to switch to apple juice or the competitor’s smoothie if it is cheaper.
- 激励功能： Mia有动力寻找更便宜的替代品或提高效率。消费者有动力转向苹果汁或竞争者的果昔，如果它们更便宜的话。
In this way, no central planner is needed; the price system coordinates the decisions of countless individuals through changing relative prices.
这样一来，就不需要中央计划者；价格体系通过相对价格的变化，协调无数个体的决策。
7. Introducing Price Elasticity of Supply | 价格供给弹性简介
We looked at demand elasticity earlier; supply also has elasticity. Price elasticity of supply (PES) measures how responsive the quantity supplied is to a change in price. In the short run, FruitFlow’s supply is likely to be inelastic – Mia cannot suddenly double her smoothie output even if the price shoots up, because she has a fixed blender, limited fridge space and only one pair of hands.
我们之前分析了需求弹性；供给也有弹性。供给价格弹性（PES）衡量供给量对价格变化的反应程度。在短期内，FruitFlow的供给很可能缺乏弹性——即使价格飙升，Mia也无法突然将果昔产量翻倍，因为她的搅拌机固定、冰箱空间有限，而且只有一双手。
We can show PES with a similar formula:
Price Elasticity of Supply (PES) = (% Change in Quantity Supplied) ÷ (% Change in Price)
我们可以用类似的公式表示PES：
供给价格弹性（PES）= （供给量变化百分比）÷ （价格变化百分比）
If the smoothie price rises by 20% but Mia can only increase output by 5% immediately, her PES is 0.25 – highly inelastic. Over a longer period, however, she can buy more blenders, hire an assistant and source additional fruit, making supply more elastic. Understanding this time dimension is crucial in case studies.
如果果昔价格上涨20%，但Mia只能立即将产量提高5%，她的PES为0.25——高度缺乏弹性。然而，经过一段较长时间，她可以购买更多搅拌机、雇用助手并采购更多水果，使供给变得更富弹性。理解这个时间维度对案例分析至关重要。
8. Government Intervention: A Sugar Tax on Smoothies? | 政府干预：是否对果昔征收糖税？
Imagine the government introduces a tax on drinks with added sugar, aiming to reduce obesity. Even though FruitFlow uses natural fruit, some of its recipes include honey or frozen yogurt that contain sugar. A new indirect tax would shift the supply curve leftward again, because the tax adds to production costs per unit sold.
假设政府为了减少肥胖，对含添加糖的饮品征税。尽管FruitFlow使用天然水果，但其部分配方包含蜂蜜或含糖冷冻酸奶。一项新的间接税将再次使供给曲线左移，因为税收增加了每售出一单位的成本。
The impact of the tax depends on the price elasticity of demand and supply. Because demand for Mia’s smoothies is elastic, the firm would find it hard to pass the full tax onto consumers. If she raised the price by the full amount of the tax, many customers would stop buying. The tax burden would therefore fall mainly on FruitFlow, reducing its already slim profit margin.
税收的影响取决于需求与供给的价格弹性。由于Mia果昔的需求富有弹性，企业将难以把全部税收转嫁给消费者。如果她将价格提高等同于税额的幅度，很多顾客就会停止购买。因此，税收负担将主要落在FruitFlow身上，进一步压缩它本已微薄的利润空间。
This real‑world twist shows why businesses and economists must think about the incidence of taxation, not just its existence. Mia might respond by adjusting her recipe to be tax‑exempt or by clearly labelling her products as 'no added sugar'.
这个现实转折点表明，为什么企业和经济学家必须考虑税收的归宿，而不仅仅是税收的存在。Mia的应对措施可能是调整配方使其免税，或者在产品上清晰地标注“无添加糖”。
9. Evaluating Business Decisions: Opportunity Cost and Trade‑offs | 评估商业决策：机会成本与权衡
Mia is considering three options to deal with the strawberry price rise: (A) raise smoothie prices, (B) keep price unchanged but use less strawberry and more banana, or (C) temporarily stop selling strawberry smoothies and focus on a new mango variety. Every choice involves a trade‑off, and the opportunity cost is the value of the next best alternative forgone.
Mia正在考虑应对草莓涨价的三个方案：(A) 提高果昔价格，(B) 维持价格不变但减少草莓用量、增加香蕉用量，或 (C) 暂时停售草莓果昔，转而主打新款芒果果昔。每个方案都涉及权衡，而机会成本就是所放弃的次优选项的价值。
- If she chooses A, the opportunity cost is the customer goodwill and loyalty lost if sales drop, plus the possible boost in reputation she might have gained by innovating with recipe B.
- 如果选择A，机会成本是销量下滑所丧失的顾客好感和忠诚度，加上她通过B方案的配方创新可能获得的声誉提升。
- If she chooses B, the opportunity cost is the potential revenue from temporarily embracing the mango trend (option C) and the chance to reposition the brand.
- 如果选择B，机会成本是暂时拥抱芒果趋势（方案C）可能带来的收入，以及重新定位品牌的机会。
- If she chooses C, the opportunity cost is the steady income from strawberry loyalists and the risk that they will permanently switch to the competitor.
- 如果选择C，机会成本是草莓忠实顾客带来的稳定收入，以及他们可能永久转向竞争者的风险。
A strong case study answer will not just state the opportunity cost; it will explain why a particular cost is significant and how it might influence the final decision.
一份出色的案例分析答案不会仅仅陈述机会成本，还会解释为什么某项成本很重要，以及它会如何影响最终决策。
10. Mixed Economy and the Role of the Public Sector | 混合经济与公共部门的作用
FruitFlow operates within a mixed economy, where both private sector firms and the government make economic decisions. While Mia’s business is part of the private sector, the government provides the legal framework, enforces food safety standards, and may influence the market through taxes and subsidies. A subsidy on locally grown fruit could lower Mia’s costs, shifting the supply curve to the right.
FruitFlow在混合经济中运营，私营部门企业和政府共同作出经济决策。虽然Mia的企业属于私营部门，但政府提供了法律框架，执行食品安全标准，并可能通过税收和补贴影响市场。对本地种植水果的补贴可以降低Mia的成本，使供给曲线右移。
Public goods, such as the roads Mia uses to deliver her smoothies and the street lighting at the farmers’ market, are provided by the state because they are non‑rival and non‑excludable – the free market would under‑provide them. Mia benefits from these without directly paying for each use, illustrating the interdependence between private enterprise and public services.
公共物品，如Mia运送果昔所使用的道路和农贸市场的路灯，由国家提供，因为它们具有非竞争性和非排他性——自由市场会提供不足。Mia从中受益却无需为每次使用直接付费，这说明了私营企业与公共服务之间的相互依存关系。
Understanding this wider context helps students see that no business operates in a vacuum; government policy is often a key variable in a case study analysis.
了解这一更广阔的背景，有助于学生认识到没有任何企业能在真空中运营；政府政策往往是案例分析中的一个关键变量。
11. Model Answers to Common Case Study Questions | 常见案例分析问题模型答案
Let us practise with three typical AQA‑style questions based on FruitFlow. Read the question, identify the command word (explain, analyse, evaluate) and use the chains of reasoning we have built.
让我们基于FruitFlow练习三道典型的AQA风格问题。阅读题目，识别指令词（解释、分析、评估），并运用我们构建好的推理链条。
Question 1: Explain why a rise in strawberry prices is likely to reduce the supply of FruitFlow smoothies. (4 marks)
Model answer: A rise in strawberry prices increases the cost of production for FruitFlow. This means that at any given selling price, the firm’s profit per smoothie falls. As producers are motivated by profit, Mia will be less willing and able to supply the same quantity as before. Therefore, the supply curve shifts to the left, and quantity supplied decreases at every price point.
问题1： 解释为什么草莓价格上涨很可能减少FruitFlow果昔的供给。（4分）
模型答案： 草莓价格上涨增加了FruitFlow的生产成本。这意味着在任何给定的销售价格下，企业每杯果昔的利润都会下降。由于生产者受利润驱动，Mia愿意和能够供应的数量将不如从前。因此，供给曲线向左移动，在每一价格点上的供给量都会减少。
Question 2: Analyse the impact of a new competitor on the equilibrium price and quantity in the smoothie market. (6 marks)
Model answer: The entry of a new competitor increases the number of substitutes available to consumers. This makes demand for FruitFlow’s smoothies more elastic and shifts the demand curve facing FruitFlow to the left, as some customers switch. With an unchanged supply curve, the new equilibrium will show a lower price and a lower quantity sold by FruitFlow. The market overall may see total quantity rise, but Mia’s share decreases. A diagram would show a leftward shift of the demand curve for FruitFlow’s product.
问题2： 分析新竞争者进入对果昔市场均衡价格和均衡数量的影响。（6分）
模型答案： 新竞争者进入增加了消费者可获得的替代品数量。这使得FruitFlow果昔的需求变得更富弹性，并导致FruitFlow面临的需求曲线向左移动，因为部分顾客转向了竞争者。在原供给曲线不变的情况下，新的均衡将显示出更低的价格和更少的FruitFlow销售量。整个市场总销量可能上升，但Mia的份额下降。图表将显示FruitFlow产品的需求曲线向左移动。
Question 3: Evaluate whether FruitFlow should raise its smoothie price in response to rising ingredient costs. (9 marks)
Model answer: On one hand, raising the price could help maintain profit margins per cup and signal premium quality. However, because demand is price elastic (PED > 1), the quantity demanded would fall proportionally more, likely reducing total revenue. Additionally, the presence of a close competitor means customers can easily switch, which could permanently damage market share. Lowering the price or keeping it stable while reformulating the recipe might protect volume and long‑term loyalty. The best strategy depends on Mia’s objective – if she wants to maximise short‑run profit, a small price rise might work only if accompanied by successful differentiation. Overall, given the elastic demand and competitive pressure, I recommend keeping price unchanged and focusing on cost control and product innovation to preserve market position.
问题3： 评估FruitFlow是否应该为应对原料成本上涨而提高果昔价格。（9分）
模型答案： 一方面，提价有助于维持每杯的利润率，并传递优质产品的信号。然而，由于需求富有价格弹性（PED > 1），需求量的下降幅度会超过价格上升幅度，这很可能会降低总收入。此外，有一家势均力敌的竞争者存在，意味着顾客可以轻易转向别家，这可能永久性地损害市场份额。降价或保持价格不变同时调整配方，则可能保住销量和长期忠诚度。最佳策略取决于Mia的目标——如果她想最大化短期利润，小幅提价只有在成功实现产品差异化的情况下才可能奏效。总体而言，考虑到弹性需求和竞争压力，我建议保持价格不变，转而集中精力控制成本和创新产品，以保住市场地位。
12. Top Tips for Acing Case Study Exams | 案例分析考试高分要点
Always begin by identifying the economic concepts the case is testing. Look for keywords like ‘cost’, ‘price’, ‘competition’, ‘tax’, ‘shortage’ – they are clues. Structure your answers using the D‑E‑E‑L framework: Define the key term, Explain the mechanism, give an Example from the case, and Link back to the question. Use diagrams where relevant, even if the question does not explicitly ask for one – a correctly labelled supply‑and‑demand diagram adds clarity and can earn extra marks.
永远从识别案例所考察的经济概念入手。寻找诸如“成本”、“价格”、“竞争”、“税收”、“短缺”等关键词——它们都是线索。使用D‑E‑E‑L框架组织答案：定义关键术语，解释机制，引用案例中的例子，并回链题目。即使题目没有明确要求，也尽量使用相关图表——一个标注正确的供需图能增加答案的清晰度，并可能赢得额外分数。
Time management is crucial. A 4‑mark ‘explain’ question should take about 4‑5 minutes; a 9‑mark ‘evaluate’ question needs 10‑12 minutes of planning, writing and checking. Leave two minutes at the end to read your answers and correct any confused chains of reasoning. And lastly, always think like an economist: ask ‘What trade‑offs exist?’, ‘Who bears the cost?’ and ‘What happens next?’. That habit alone will transform your case study performance.
时间管理至关重要。一道4分的“解释”题大约需要4-5分钟；一道9分的“评估”题则需要10-12分钟用于计划、写作和检查。最后留出两分钟通读答案，纠正任何逻辑混乱的推理链条。最后，一直像经济学家那样思考：追问“存在哪些权衡？”、“成本由谁承担？”以及“接下来会发生什么？”。单是这个习惯就能让你的案例分析表现脱胎换骨。
Published by TutorHao | Economics Revision Series | aleveler.com
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