📚 GCSE CIE Economics: Calculation Practice Drill | GCSE CIE 经济：计算题专项训练
Mastering the calculation questions in CIE GCSE Economics is essential for achieving a high grade. This drill consolidates every key formula and technique you need, from percentage changes and elasticities to break‑even analysis and exchange rates. Work through each section carefully, and always show your steps clearly.
掌握 CIE GCSE 经济中的计算题是取得高分的关键。本训练收录了你需要掌握的每一项核心公式和技巧，涵盖百分比变化、弹性、盈亏平衡分析及汇率计算等内容。请认真完成每个小节，并始终清晰展示你的解题步骤。
1. Percentage Changes: The Foundation | 百分比变化：基础
Almost every economic calculation begins with a percentage change. The formula is straightforward: take the difference between the new value and the original value, divide by the original value, then multiply by 100.
几乎所有的经济计算都从百分比变化开始。公式很简单：用新值减去原值，除以原值，再乘以 100。
%Δ = (New – Original) ÷ Original × 100
%Δ = (新值 – 原值) ÷ 原值 × 100
For example, if the price of a textbook rises from £20 to £25, the percentage change in price is (25 – 20) ÷ 20 × 100 = 25% s check whether the result is an increase or a decrease; a negative sign indicates a fall.
例如，某本教材的价格从 20 英镑上涨到 25 英镑，价格变化的百分比为 (25 – 20) ÷ 20 × 100 = 25%。务必注意结果是上升还是下降——负号代表下降。
This tool is the backbone of elasticity, inflation, and unemployment calculations. Practise with quantities, prices, and incomes until you can apply it without hesitation.
这一工具是弹性、通货膨胀和失业率计算的基石。多用量、价格和收入进行练习，直到你能毫不犹豫地运用它。
2. Price Elasticity of Demand (PED) | 需求价格弹性 (PED)
Price elasticity of demand measures how responsive quantity demanded is to a change in price. The formula uses two percentage changes.
需求价格弹性衡量的是需求量对价格变化的反应程度。该公式使用了两个百分比变化。
PED = %Δ in Quantity Demanded ÷ %Δ in Price
PED = 需求量变化的百分比 ÷ 价格变化的百分比
cts you to use the absolute value when interpreting the coefficient. For instance, if a 10% price rise leads to a 5% fall in quantity demanded, PED = –0.5. Ignoring the sign, 0.5 indicates inelastic demand.
由于价格与需求量通常呈反向变动，PED 通常为负数。但 CIE 经常要求你在解释系数时使用绝对值。例如，若价格上升 10% 导致需求量下降 5%，则 PED = –0.5。忽略符号，0.5 表示需求缺乏弹性。
| Numerical PED (absolute) | Interpretation | 中文解释 |
| 0 | Perfectly inelastic | 完全无弹性 |
| Between 0 and 1 | Inelastic | 缺乏弹性 |
| 1 | Unit elastic | 单位弹性 |
| Greater than 1 | Elastic | 富有弹性 |
| Infinity | Perfectly elastic | 完全有弹性 |
Worked example: A café reduces its coffee price from £3.00 to £2.40 (a 20% decrease). Daily sales increase from 200 cups to 260 cups (a 30% increase). PED = 30% ÷ –20% = –1.5. The absolute value is 1.5, so demand is elastic.
练习题：一家咖啡馆将咖啡单价从 3.00 英镑降至 2.40 英镑（降价 20%），每日销量从 200 杯升至 260 杯（上涨 30%）。PED = 30% ÷ –20% = –1.5。绝对值为 1.5，因此需求富有弹性。
3. Price Elasticity of Supply (PES) | 供给价格弹性 (PES)
Price elasticity of supply measures how responsive quantity supplied is to a price change. It uses a similar structure to PED.
供给价格弹性衡量的是供给量对价格变化的反应程度。它的结构与 PED 类似。
PES = %Δ in Quantity Supplied ÷ %Δ in Price
PES = 供给量变化的百分比 ÷ 价格变化的百分比
Unlike PED, PES is usually positive because higher prices encourage firms to supply more. A PES greater than 1 signals elastic supply; less than 1 signals inelastic supply.
与 PED 不同，PES 通常为正，因为高价会激励厂商增加供给。PES 大于 1 表示供给富有弹性；小于 1 则表示供给缺乏弹性。
Example: The market price of wheat rises by 15%. Farmers increase their output by 9%. PES = 9% ÷ 15% = 0.6, implying supply is inelastic in the short run.
示例：小麦市场价格上涨 15%，农民将产量提高 9%。PES = 9% ÷ 15% = 0.6，说明短期内供给缺乏弹性。
4. Income Elasticity of Demand (YED) | 需求收入弹性 (YED)
Income elasticity of demand captures how quantity demanded changes when consumer income changes. It helps classify goods as normal or inferior.
需求收入弹性反映的是需求量如何随消费者收入的变化而变动，有助于将商品划分为正常品或低档品。
YED = %Δ in Quantity Demanded ÷ %Δ in Income
YED = 需求量变化的百分比 ÷ 收入变化的百分比
A positive YED indicates a normal good. If YED is greater than 1, the good is a luxury; if between 0 and 1, it is a necessity. A negative YED identifies an inferior good.
YED 为正代表正常品。若 YED 大于 1，该商品为奢侈品；若介于 0 与 1 之间，则为必需品。YED 为负则代表低档品。
Example: Average incomes rise by 4%. Demand for budget bus travel falls by 6%. YED = –6% ÷ 4% = –1.5. The negative sign shows bus travel is an inferior good.
示例：平均收入上升 4%，廉价巴士出行的需求下降 6%。YED = –6% ÷ 4% = –1.5。负号表明巴士出行属于低档品。
5. Total Revenue and Elasticity | 总收益与弹性
Total revenue (TR) is the amount a firm receives from sales, calculated simply as price multiplied by quantity sold.
总收益 (TR) 是企业从销售中获得的收入，直接由价格乘以销量得出。
Total Revenue = Price × Quantity
总收益 = 单价 × 数量
The relationship between PED and TR is a favourite exam topic. If demand is elastic (PED > 1), a price cut raises total revenue because the percentage increase in quantity demanded outweighs the percentage price drop. Conversely, if demand is inelastic, a price rise will increase TR.
PED 与 TR 之间的关系是常考考点。若需求富有弹性（PED > 1），降价将提高总收益，因为需求量上升的百分比超过了价格下降的百分比。反之，若需求缺乏弹性，提价将会增加总收益。
Illustration: A cinema sells 400 tickets per day at £8.00 each, yielding TR = £3,200. The manager estimates PED = –2.5 and decides to lower the price by 10% to £7.20. The quantity demanded rises by 25% (because 2.5 × 10%) to 500 tickets. New TR = 500 × £7.20 = £3,600. The price cut raised total revenue, confirming elastic demand.
示例：一家影院每天以 £8.00 的价格售出 400 张票，TR = £3,200。经理估计 PED = –2.5，决定降价 10% 至 £7.20。需求量上升 25%（由于 2.5 × 10%）至 500 张票。新的 TR = 500 × £7.20 = £3,600。降价提高了总收益，证实了需求富有弹性。
6. Costs, Revenue and Profit | 成本、收益与利润
Profit is the reward for risk‑taking, and calculating it requires a clear grip on costs and revenue. The three key equations are:
利润是对承担风险的回报，计算利润需要清楚掌握成本与收益。以下是三个核心等式：
Total Cost (TC) = Total Fixed Cost (TFC) + Total Variable Cost (TVC)
总成本 (TC) = 总固定成本 (TFC) + 总变动成本 (TVC)
Average Total Cost (ATC) = Total Cost ÷ Output
平均总成本 (ATC) = 总成本 ÷ 产量
Profit = Total Revenue – Total Cost
利润 = 总收益 – 总成本
Worked example: A bakery has monthly fixed costs of £2,000. The variable cost per loaf is £0.80, and it produces 5,000 loaves. Each loaf sells for £1.50. TVC = 5,000 × £0.80 = £4,000, so TC = £2,000 + £4,000 = £6,000. TR = 5,000 × £1.50 = £7,500. Therefore, profit = £7,500 – £6,000 = £1,500. ATC = £6,000 ÷ 5,000 = £1.20 per loaf.
练习题：一家面包店月固定成本为 £2,000。每条面包的变动成本为 £0.80，本月生产了 5,000 条。每条售价 £1.50。TVC = 5,000 × £0.80 = £4,000，所以 TC = £2,000 + £4,000 = £6,000。TR = 5,000 × £1.50 = £7,500。因此利润 = £7,500 – £6,000 = £1,500。ATC = £6,000 ÷ 5,000 = 每条 £1.20。
7. Break‑even Analysis | 盈亏平衡分析
Break‑even occurs when total revenue equals total cost, meaning the firm makes neither a profit nor a loss. The formula hinges on the contribution per unit.
盈亏平衡点出现在总收益等于总成本时，此时企业既不盈利也不亏损。其公式取决于每单位的贡献。
Break‑even Output = Total Fixed Cost ÷ (Selling Price – Variable Cost per Unit)
盈亏平衡产量 = 总固定成本 ÷ （单价 – 单位变动成本）
The term (Price – Variable Cost per Unit) is called the contribution per unit. It is the amount each sale contributes towards covering fixed costs.
（单价 – 单位变动成本）称为单位贡献，即每售出一件产品对收回固定成本所作的贡献。
Example: A sportswear brand has annual fixed costs of £100,000. Its jackets sell for £60 each, and the variable cost per jacket is £35. Contribution per unit = £60 – £35 = £25. Break‑even output = £100,000 ÷ £25 = 4,000 jackets. The firm must sell 4,000 jackets per year just to cover all costs.
示例：某运动品牌年固定成本为 £100,000。其夹克单价为 £60，每件变动成本为 £35。单位贡献 = £60 – £35 = £25。盈亏平衡产量 = £100,000 ÷ £25 = 4,000 件。该企业每年须至少卖出 4,000 件夹克才能覆盖全部成本。
8. Inflation Rate and CPI | 通货膨胀率与消费者物价指数
The inflation rate shows how fast the general price level is rising. It is most commonly calculated using the Consumer Price Index (CPI).
通货膨胀率反映一般物价水平的上涨速度，通常通过消费者物价指数（CPI）来计算。
Inflation Rate = (CPI in Current Year – CPI in Previous Year) ÷ CPI in Previous Year × 100
Published by TutorHao | GCSE Economics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图