Year 8 CAIE Economics Formula & Theorem Quick Reference Handbook | Year 8 CAIE 经济公式定理速查手册

📚 Year 8 CAIE Economics Formula & Theorem Quick Reference Handbook | Year 8 CAIE 经济公式定理速查手册

Welcome to your Year 8 CAIE Economics revision guide – a compact collection of essential formulas and theorems. Mastering these will help you analyse real-world economic situations and perform well in assessments. Each entry is presented in English first, followed by the Chinese version, so you can learn key terms in both languages.

欢迎使用 Year 8 CAIE 经济复习手册——这是一本浓缩了核心公式与定理的速查指南。掌握这些内容将帮助你分析现实经济问题，并在考试中取得理想成绩。每个条目都先以英文呈现，再附中文对照，方便你双语学习关键术语。

1. Basic Economic Concepts and Scarcity | 基本经济概念与稀缺性

The fundamental economic problem is scarcity: unlimited wants versus limited resources. This forces individuals, firms, and governments to make choices, incurring an opportunity cost – the value of the next best alternative forgone.

基本的经济问题是稀缺性：无限的欲望与有限的资源之间的矛盾。这迫使个人、企业和政府做出选择，并产生机会成本——即放弃的次优选择的价值。

The opportunity cost formula is:

机会成本的公式为：

Opportunity Cost = Value of Next Best Alternative Given Up

机会成本 = 放弃的次优选择的价值

Scarcity is not the same as shortage. Shortage is temporary and can be resolved by rising prices, while scarcity is permanent.

稀缺性不等于短缺。短缺是暂时的，可以通过价格上涨解决，而稀缺性是永久性的。

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2. Factors of Production | 生产要素

Resources used to produce goods and services are classified into four factors of production: land, labour, capital, and entrepreneurship. The reward for each factor is rent, wages/salaries, interest, and profit respectively.

用于生产商品和服务的资源分为四种生产要素：土地、劳动力、资本和企业家才能。各要素的报酬分别为地租、工资/薪水、利息和利润。

• Land – all natural resources (minerals, water, forests). Reward: Rent.
• 土地——所有自然资源（矿产、水、森林）。报酬：地租。
• Labour – human effort, both physical and mental. Reward: Wages/Salaries.
• 劳动力——人类的体力和脑力付出。报酬：工资/薪水。
• Capital – man-made tools, machinery, factories used to produce other goods. Reward: Interest.
• 资本——用于生产其他商品的人造工具、机器、工厂。报酬：利息。
• Entrepreneurship – the ability to combine the other three factors, take risks, and innovate. Reward: Profit.
• 企业家才能——组合其他三种要素、承担风险并进行创新的能力。报酬：利润。

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3. Demand and Supply | 需求与供给

The law of demand states that, ceteris paribus, as price falls, quantity demanded increases, and vice versa. The law of supply states that, ceteris paribus, as price rises, quantity supplied increases, and vice versa.

需求定律指出，在其他条件不变的情况下，价格下降，需求量增加；反之亦然。供给定律指出，在其他条件不变的情况下，价格上升，供给量增加；反之亦然。

Demand function: Q_d = a − bP, where a is the intercept (when P=0), b is the slope.

需求函数：Q_d = a − bP，其中 a 是截距（当 P=0 时），b 是斜率。

Supply function: Q_s = c + dP, where c is the intercept (when P=0), d is the slope.

供给函数：Q_s = c + dP，其中 c 是截距（当 P=0 时），d 是斜率。

A change in price causes a movement along the curve. A change in non-price factors (income, tastes, technology, costs of production, etc.) shifts the entire curve.

价格变化导致沿曲线的移动。非价格因素（收入、偏好、技术、生产成本等）的变化导致整条曲线移动。

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4. Market Equilibrium | 市场均衡

Market equilibrium occurs where quantity demanded equals quantity supplied. At this point, there is no tendency for price to change.

市场均衡发生在需求量等于供给量时。此时，价格没有变化的趋势。

Q_d = Q_s

A shortage (excess demand) puts upward pressure on price. A surplus (excess supply) puts downward pressure on price.

短缺（超额需求）给价格带来上涨压力。过剩（超额供给）给价格带来下跌压力。

Changes in demand or supply disrupt equilibrium, creating a new equilibrium price and quantity. The process is automatic in a free market economy.

需求或供给的变化会打破均衡，形成新的均衡价格和数量。在自由市场经济中，这一过程是自动发生的。

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5. Price Elasticity of Demand | 需求价格弹性

Price elasticity of demand (PED) measures the responsiveness of quantity demanded to a change in price. Formula:

需求价格弹性（PED）衡量需求量对价格变化的反应程度。公式为：

PED = (% Δ Q_d) ÷ (% Δ P)

• |PED| > 1: elastic (quantity changes more than price)
• |PED| > 1：富有弹性（数量的变化幅度大于价格）
• |PED| < 1: inelastic (quantity changes less than price)
• |PED| < 1：缺乏弹性（数量的变化幅度小于价格）
• |PED| = 1: unit elastic (proportional change)
• |PED| = 1：单位弹性（同比例变化）
• |PED| = 0: perfectly inelastic
• |PED| = 0：完全无弹性
• |PED| = ∞: perfectly elastic
• |PED| = ∞：完全弹性

Note: Year 8 often introduces the concept using percentage changes, but you can also use the midpoint formula for more accuracy.

注意：Year 8 通常用百分比变化引入这个概念，但你也可以使用中点公式以获得更精确的结果。

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6. Costs and Revenue | 成本与收入

Total cost (TC) is the sum of all expenses incurred in production. It is divided into fixed costs (FC) – which do not vary with output – and variable costs (VC) – which vary directly with output.

总成本（TC）是生产中发生的所有费用的总和。它分为固定成本（FC）——不随产量变化——和可变成本（VC）——直接随产量变化。

TC = FC + VC

总成本 = 固定成本 + 可变成本

Average cost (AC) is the cost per unit of output:

平均成本（AC）是每单位产量的成本：

AC = TC ÷ Q

平均成本 = 总成本 ÷ 产量

Total revenue (TR) is the income a firm receives from selling its products:

总收入（TR）是企业从销售产品中获得的收入：

TR = Price × Quantity Sold

总收入 = 价格 × 销售量

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7. Profit and Loss | 利润与亏损

Profit is the reward for entrepreneurship. It is the difference between total revenue and total cost.

利润是企业家才能的报酬，它是总收入与总成本之间的差额。

Profit (π) = TR − TC

利润 (π) = 总收入 − 总成本

If TR > TC, the firm makes a profit. If TR < TC, the firm makes a loss.

如果总收入大于总成本，企业盈利。如果总收入小于总成本，企业亏损。

Break-even point occurs when TR = TC, so profit is zero.

盈亏平衡点出现在总收入等于总成本时，此时利润为零。

You can also express profit as:

利润也可以表示为：

Profit = (Price − Average Cost) × Q

利润 = (价格 − 平均成本) × 产量

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8. Economic Systems | 经济体系

Every economy must answer three basic questions: What to produce? How to produce? For whom to produce? The way a society answers these defines its economic system.

每个经济体都必须回答三个基本问题：生产什么？如何生产？为谁生产？一个社会回答这些问题的方式决定了其经济体系。

• Market economy: decisions are made by private individuals and firms based on price signals. Also called capitalism.
• 市场经济：决策由私人个体和企业根据价格信号做出。也称为资本主义。
• Command economy: government makes all economic decisions. Also called planned economy or socialism.
• 指令经济：政府做出所有经济决策。也称为计划经济或社会主义。
• Mixed economy: combines elements of both market and command systems. Most real-world economies are mixed.
• 混合经济：结合了市场和指令体系的元素。现实世界中大多数经济体都是混合经济。

The invisible hand is a metaphor introduced by Adam Smith to describe the self-regulating nature of the marketplace.

“看不见的手”是亚当·斯密提出的比喻，用以描述市场的自我调节特性。

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9. Money and Banking | 货币与银行

Money serves three main functions: medium of exchange, unit of account, and store of value. Banks act as financial intermediaries, accepting deposits and making loans.

货币具有三大职能：交换媒介、计价单位和价值储藏。银行作为金融中介，接受存款并发放贷款。

The simple deposit multiplier shows how banks can create money through lending:

简单的存款乘数显示了银行如何通过放贷创造货币：

Money Multiplier = 1 ÷ Reserve Requirement Ratio

货币乘数 = 1 ÷ 存款准备金率

For example, if the reserve requirement is 10% (0.10), the maximum amount of money the banking system can create from an initial deposit is 10 times that deposit.

例如，如果准备金率为 10% (0.10)，银行系统从初始存款最多能创造相当于初始存款 10 倍的货币。

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10. International Trade | 国际贸易

Countries trade because they have different opportunity costs, leading to comparative advantage. A country should specialise in producing goods where it has a lower opportunity cost.

国家之间进行贸易是因为它们的机会成本不同，从而产生了比较优势。一国应专门生产机会成本较低的商品。

The terms of trade refer to the ratio at which a country can trade its exports for imports:

贸易条件是指一国用出口换进口商品的比率：

Terms of Trade = (Index of Export Prices ÷ Index of Import Prices) × 100

贸易条件 = (出口价格指数 ÷ 进口价格指数) × 100

An improvement in terms of trade means a country can buy more imports for a given quantity of exports.

贸易条件的改善意味着一国用一定数量的出口可以买到更多的进口商品。

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11. Macroeconomic Indicators | 宏观经济指标

Gross Domestic Product (GDP) measures the total value of all final goods and services produced within a country in a given period. The basic expenditure formula is:

国内生产总值（GDP）衡量一个国家在一定时期内生产的所有最终商品和服务的总价值。基本的支出法公式为：

GDP = C + I + G + (X − M)

GDP = 消费 + 投资 + 政府支出 + (出口 − 进口)

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。

Unemployment rate is the percentage of the labour force that is without a job but actively seeking work.

失业率是劳动力中没有工作但正在积极寻找工作的人所占的百分比。

Unemployment Rate = (Number of Unemployed ÷ Labour Force) × 100

失业率 = (失业人数 ÷ 劳动力人数) × 100

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12. Inflation | 通货膨胀

Inflation is a sustained increase in the general price level. It reduces the purchasing power of money. The inflation rate is the percentage change in a price index, such as CPI.

通货膨胀是指一般价格水平的持续上升，它降低了货币的购买力。通货膨胀率是价格指数（如居民消费价格指数 CPI）变动的百分比。

Inflation Rate = [(CPI_current − CPI_previous) ÷ CPI_previous] × 100

通货膨胀率 = [(当期 CPI − 上期 CPI) ÷ 上期 CPI] × 100

Disinflation means inflation is still positive but rising at a slower rate. Deflation is a persistent fall in the general price level (negative inflation).

通货减速意味着通货膨胀率仍为正，但上升速度放缓。通货紧缩是一般价格水平持续下跌（负通货膨胀）。

Central banks use monetary policy (interest rates, money supply) to control inflation. A common target is around 2%.

中央银行利用货币政策（利率、货币供应量）来控制通货膨胀。常见的目标约为 2%。

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Published by TutorHao | Economics Revision Series | aleveler.com

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