📚 Year 10 OCR Economics: Formula and Theorem Quick Reference Handbook | Year 10 OCR 经济：公式定理速查手册
This handbook gathers all the essential formulas and key economic relationships you need for Year 10 OCR GCSE Economics. It is designed as a one‑stop revision aid, linking each formula to a clear explanation so you can apply them confidently in exam questions.
本手册汇集了 Year 10 OCR GCSE 经济学所需的所有核心公式和关键经济关系。它设计为一份一站式复习工具，将每个公式与清晰的解释联系起来，使你在考试题目中能够自信运用。
1. Price Elasticity of Demand (PED) | 需求价格弹性
Price elasticity of demand measures the responsiveness of quantity demanded to a change in price. It is calculated by dividing the percentage change in quantity demanded by the percentage change in price.
需求价格弹性衡量需求量对价格变化的反应程度。它用需求量的百分比变化除以价格的百分比变化来计算。
PED = %ΔQd ÷ %ΔP
- When PED > 1, demand is elastic – a price cut raises total revenue.
- 当 PED > 1 时，需求富有弹性 – 降价会增加总收益。
- When PED < 1, demand is inelastic – a price rise increases total revenue.
- 当 PED < 1 时，需求缺乏弹性 – 提价会增加总收益。
- When PED = 1, demand is unit elastic – revenue stays the same when price changes.
- 当 PED = 1 时，需求具有单位弹性 – 价格变动时收益不变。
2. Price Elasticity of Supply (PES) | 供给价格弹性
Price elasticity of supply shows how much the quantity supplied responds to a change in price. It uses the same structure as PED but focuses on the supply side.
供给价格弹性表示供给量对价格变化的反应程度。计算结构与 PED 相同，但侧重于供给侧。
PES = %ΔQs ÷ %ΔP
- PES > 1 indicates elastic supply – producers can increase output quickly.
- PES > 1 表示供给富有弹性 – 生产者能够快速增加产出。
- PES < 1 indicates inelastic supply – output is slow to adjust.
- PES < 1 表示供给缺乏弹性 – 产出调整缓慢。
3. Income Elasticity of Demand (YED) | 需求收入弹性
Income elasticity of demand measures the sensitivity of demand to changes in consumers' income. It helps classify goods as normal or inferior.
需求收入弹性衡量需求对消费者收入变化的敏感程度。它有助于将商品分为正常品和劣等品。
YED = %ΔQd ÷ %ΔY
- Positive YED means the good is normal – demand rises as income rises. If YED > 1, it is a luxury.
- 正的 YED 表示该商品为正常品 – 收入上升时需求上升。YED > 1 则为奢侈品。
- Negative YED means the good is inferior – demand falls when income grows.
- 负的 YED 表示该商品为劣等品 – 收入增长时需求下降。
4. Total Revenue, Average Revenue and Marginal Revenue | 总收益、平均收益与边际收益
Revenue concepts are central to a firm's pricing and output decisions. Total revenue is the money received from sales, while average revenue equals price when all units are sold at the same price.
收益概念是厂商定价和产量决策的核心。总收益是销售获得的收入，而平均收益在相同价格销售时等于价格。
Total Revenue (TR) = Price (P) × Quantity (Q)
Average Revenue (AR) = TR ÷ Q = P
Marginal Revenue (MR) = ΔTR ÷ ΔQ
- For a price‑taking firm, MR = AR = P. For a price‑making firm, MR is below AR.
- 对于价格接受者，MR = AR = P。对于价格制定者，MR 低于 AR。
5. Costs: Fixed, Variable and Total Cost | 成本：固定成本、可变成本与总成本
Firms face different types of costs in the short run. Fixed costs do not vary with output, while variable costs change directly with the quantity produced.
企业在短期面临不同类型的成本。固定成本不随产量变化，而可变成本直接随产量变化。
Total Cost (TC) = Total Fixed Cost (TFC) + Total Variable Cost (TVC)
- Examples of fixed costs: rent, insurance, management salaries.
- 固定成本举例：租金、保险、管理人员工资。
- Examples of variable costs: raw materials, energy, packaging.
- 可变成本举例：原材料、能源、包装。
6. Average Costs and Marginal Cost | 平均成本与边际成本
Average costs tell us the cost per unit of output. Marginal cost is the extra cost of producing one more unit – crucial for finding the profit‑maximising output.
平均成本告诉我们每单位产出的成本。边际成本是再生产一单位产品所增加的成本 – 这对于寻找利润最大化产量至关重要。
Average Fixed Cost (AFC) = TFC ÷ Q
Average Variable Cost (AVC) = TVC ÷ Q
Average Total Cost (ATC) = TC ÷ Q = AFC + AVC
Marginal Cost (MC) = ΔTC ÷ ΔQ
- AFC falls continuously as output rises (spreading overheads).
- AFC 随产量上升而持续下降（分摊间接费用）。
- MC curve typically cuts ATC and AVC at their lowest points.
- MC 曲线通常在 ATC 和 AVC 的最低点与之相交。
7. Profit Maximisation: MC = MR Rule | 利润最大化：MC = MR 法则
A firm maximises profit by producing the quantity where marginal cost equals marginal revenue. If MC < MR, the firm can increase profit by producing more; if MC > MR, it should reduce output.
企业通过生产边际成本等于边际收益的产量来最大化利润。如果 MC < MR，增产可增加利润；如果 MC > MR，则应减产。
Profit maximising condition: MC = MR
- This rule applies to all market structures, though the shape of MR differs.
- 该法则适用于所有市场结构，只是 MR 曲线的形状有所不同。
- Total Profit = TR − TC. Profit per unit = AR − ATC.
- 总利润 = TR − TC。单位利润 = AR − ATC。
8. National Income: Expenditure Approach | 国民收入：支出法
In macroeconomics, national income can be measured by adding up all spending on final goods and services. The expenditure method is widely used in the circular flow model.
在宏观经济学中，国民收入可以通过加总所有最终产品与服务的支出来衡量。支出法在循环流转模型中被广泛使用。
GDP = C + I + G + (X − M)
where C = consumption, I = investment, G = government spending, X = exports, M = imports.
其中 C = 消费，I = 投资，G = 政府支出，X = 出口，M = 进口。
- If exports exceed imports, net exports (X − M) are positive, adding to GDP.
- 如果出口大于进口，净出口 (X − M) 为正，增加 GDP。
9. Rate of Inflation | 通货膨胀率
Inflation is the sustained rise in the general price level. The annual rate of inflation is calculated using a price index, such as the Consumer Prices Index (CPI).
通货膨胀是指总体物价水平的持续上涨。年通货膨胀率使用价格指数（如消费者价格指数 CPI）计算。
Inflation rate = [(CPI in year 2 − CPI in year 1) ÷ CPI in year 1] × 100%
- A positive rate means prices are rising; a negative rate signals deflation.
- 正值表示价格上涨；负值表示通货紧缩。
- The Bank of England targets 2% CPI inflation to maintain price stability.
- 英格兰银行将 CPI 通胀目标设定为 2%，以维持物价稳定。
10. Unemployment and Participation Rates | 失业率与劳动参与率
The unemployment rate measures the percentage of the labour force that is without a job but actively seeking work. The labour force participation rate tells us what share of the working‑age population is in the labour force.
失业率衡量劳动力中没有工作但正在积极寻找工作的人口比例。劳动参与率则表示适龄工作人口中进入劳动力市场的比例。
Unemployment rate = (Number of unemployed ÷ Labour force) × 100%
Participation rate = (Labour force ÷ Working‑age population) × 100%
- The labour force includes both employed and unemployed people.
- 劳动力包括就业者和失业者。
- An increase in the participation rate can raise potential GDP.
- 劳动参与率上升可以提高潜在 GDP。
11. Exchange Rate Conversions | 汇率换算
An exchange rate shows how much of one currency can be exchanged for another. Students need to be able to convert prices between currencies and calculate the cost of imports or exports.
汇率表示一种货币可以兑换多少另一种货币。学生需要能够在货币之间转换价格，并计算进口或出口的成本。
ount in foreign currency = Amount in home currency × Exchange rate (foreign per home unit)
- If £1 = $1.25, then £200 = 200 × 1.25 = $250.
- 如果 1 英镑 = 1.25 美元，那么 200 英镑 = 200 × 1.25 = 250 美元。
- A depreciation of the pound makes UK exports cheaper and imports more expensive.
- 英镑贬值使英国出口更便宜、进口更昂贵。
12. Opportunity Cost and the Production Possibility Frontier | 机会成本与生产可能性边界
Opportunity cost is the value of the next best alternative forgone when a choice is made. The production possibility frontier (PPF) illustrates scarcity, choice and opportunity cost by showing the maximum combinations of two goods an economy can produce.
机会成本是做出选择时所放弃的次优替代方案的价值。生产可能性边界 (PPF) 通过展示一个经济体所能生产的两种商品的最大组合，说明了稀缺性、选择和机会成本。
Opportunity cost of good X = Units of good Y given up ÷ Units of good X gained
- Moving along the PPF, producing more of one good means producing less of the other.
- 沿着 PPF 移动，多生产一种商品意味着少生产另一种商品。
- A straight‑line PPF implies constant opportunity cost; a concave PPF implies increasing opportunity cost.
- 直线 PPF 意味着机会成本不变；凹向原点的 PPF 意味着机会成本递增。
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