CIE Year 7 Economics Formula & Theorem Quick Reference Handbook | CIE 7年级经济公式定理速查手册

📚 CIE Year 7 Economics Formula & Theorem Quick Reference Handbook | CIE 7年级经济公式定理速查手册

This handbook is a concise summary of the most important formulas, definitions, and economic principles you will encounter in the CIE Year 7 Economics course. Each concept is broken down into easy-to-understand statements and paired with clear examples. Use this guide to reinforce your class notes and prepare effectively for tests and examinations.

本手册精炼总结了 CIE 7 年级经济课程中最重要的公式、定义和原理。每个概念都以简单的陈述形式呈现，并配有清晰的例子。你可以用它来巩固课堂笔记，高效备考测验和考试。

1. The Basic Economic Problem: Scarcity | 基本经济问题：稀缺性

Scarcity is the fundamental theorem of economics. It states that human wants for goods and services are unlimited, but the resources available to produce them (such as land, labour, and capital) are limited. This forces every society to answer three key questions: What to produce? How to produce? For whom to produce?

稀缺性是经济学的基本定理。它指出，人类对商品和服务的欲望是无限的，但可用于生产这些商品的资源（如土地、劳动和资本）是有限的。这迫使每个社会必须回答三个关键问题：生产什么？如何生产？为谁生产？

Because resources are scarce, we cannot have everything we want. This leads to the need for choice and the concept of opportunity cost.

由于资源稀缺，我们无法拥有想要的一切。这就引出了选择的必要性以及机会成本的概念。

2. Opportunity Cost Formula | 机会成本公式

Opportunity cost measures what you must give up when you make a choice. It is not simply the price you pay; it is the value of the next best alternative you forego.

机会成本衡量的是你做出选择时所必须放弃的东西。它不仅仅是你支付的价格，而是你所放弃的下一个最佳选择的价值。

Opportunity Cost = Value of the Next Best Alternative Foregone

机会成本 = 所放弃的下一个最优选择的价值

For example, if a student has a free hour and can either study Economics (benefit: +10 marks) or play video games (benefit: 8 utils of enjoyment), choosing to study means the opportunity cost is the 8 utils of enjoyment given up.

例如，如果一个学生有一个小时的空闲时间，他可以选择学习经济（收益：提高10分）或玩电子游戏（收益：获得8单位快乐）。选择学习意味着机会成本就是放弃的8单位快乐。

3. Factors of Production | 生产要素

Production requires inputs, known as the factors of production. Economists classify them into four broad categories, each with an associated payment or reward.

生产需要投入，即生产要素。经济学家将其分为四大类，每类都有对应的报酬或回报。

Factor 要素	Definition & Example 定义与示例	Payment 报酬
Land 土地	All natural resources used in production. e.g., farmland, oil, minerals. 生产中使用的一切自然资源。例如农田、石油、矿产。	Rent 租金
Labour 劳动	Mental and physical human effort. e.g., a teacher, a factory worker. 人类的脑力和体力付出。例如教师、工厂工人。	Wages/Salary 工资/薪水
Capital 资本	Man-made goods used to produce other goods and services. e.g., machinery, tools, buildings. 用于生产其他商品和服务的制成品。例如机器、工具、厂房。	Interest 利息
Enterprise 企业家精神	The willingness to combine the other factors and take risks. e.g., startup founder. 组合其他要素并承担风险的意愿。例如创业者。	Profit 利润

4. Production Possibility Curve (PPC) Theorems | 生产可能性曲线定理

A Production Possibility Curve (PPC) shows the maximum possible output combinations of two goods or services an economy can produce when all resources are fully and efficiently employed.

生产可能性曲线（PPC）展示了一个经济体在所有资源得到充分有效利用时，所能生产的两种商品或服务的最大可能产出组合。

Theorem 1 – Efficient Points: Any point lying exactly on the PPC represents a combination that uses all resources efficiently.

定理 1 – 效率点：位于PPC曲线上的任何一点都代表资源得到充分利用的有效组合。

Theorem 2 – Inefficient Points: Points inside the PPC mean there are idle resources or inefficient production. An economy can produce more of both goods by moving to the curve.

定理 2 – 无效率点：PPC内部的点意味着资源闲置或生产效率低下。通过向曲线移动，经济体可以增加两种商品的产量。

Theorem 3 – Unattainable Points: Points outside the PPC are unattainable given the current state of technology and resources. Economic growth (an outward shift of the curve) can make such points achievable.

定理 3 – 无法实现点：PPC外部的点在当前技术和资源条件下无法实现。经济增长（曲线向外移动）可以使这些点变得可实现。

Theorem 4 – Law of Increasing Opportunity Cost: A concave (bowed-out) PPC demonstrates that as an economy shifts resources to produce more of one good, the opportunity cost of producing additional units of that good increases.

定理 4 – 机会成本递增定律：一条凹向原点的（向外弯曲的）PPC表明，随着经济体转移资源以生产更多的一种商品，生产额外单位的这种商品的机会成本会上升。

5. The Law of Demand and The Law of Supply | 需求定律与供给定律

The market behaviour of buyers and sellers is governed by two foundational laws. These laws assume ceteris paribus (all other factors held constant).

买方和卖方的市场行为受两条基本定律支配。这些定律都基于 “其他条件不变” (ceteris paribus) 的假设。

Law of Demand:

需求定律：

As the price rises, the quantity demanded falls; as the price falls, the quantity demanded rises. (P ↑ → Qd ↓)

价格上升，需求数量下降；价格下降，需求数量上升。（P ↑ → Qd ↓）

There is an inverse relationship between price and quantity demanded. A demand curve slopes downwards from left to right.

价格与需求量呈反比关系。需求曲线从左向右下方倾斜。

Law of Supply:

供给定律：

As the price rises, the quantity supplied rises; as the price falls, the quantity supplied falls. (P ↑ → Qs ↑)

价格上升，供给数量上升；价格下降，供给数量下降。（P ↑ → Qs ↑）

There is a direct relationship between price and quantity supplied. A supply curve slopes upwards from left to right.

价格与供给量呈正比关系。供给曲线从左向右上方倾斜。

6. Market Equilibrium | 市场均衡

Equilibrium occurs at the point where the demand curve and the supply curve intersect. At this price, the quantity that buyers want to buy exactly equals the quantity that sellers want to sell. There is neither a surplus (excess supply) nor a shortage (excess demand).

均衡发生在需求曲线和供给曲线相交的点上。在这个价格下，买方愿意购买的数量恰好等于卖方愿意出售的数量。市场上不存在过剩（超额供给）或短缺（超额需求）。

Equilibrium Condition: Quantity Demanded (Qd) = Quantity Supplied (Qs)

均衡条件：需求数量 (Qd) = 供给数量 (Qs)

If the market price is set above the equilibrium price, a surplus will put downward pressure on price. If the market price is below the equilibrium price, a shortage will drive the price upwards. The market always tends to move back towards the equilibrium point.

如果市场价格高于均衡价格，过剩会产生价格下行压力。如果市场价格低于均衡价格，短缺会推动价格上行。市场总是倾向于回归均衡点。

7. Price Elasticity of Demand (PED) – Basic Formula | 需求价格弹性基础公式

Price elasticity of demand measures how responsive quantity demanded is to a change in price. Knowing elasticity helps businesses decide whether to raise or lower prices to increase total revenue.

需求价格弹性衡量的是需求量对价格变化的反应程度。了解弹性有助于企业决定是提价还是降价以增加总收入。

PED = (% Change in Quantity Demanded) / (% Change in Price)

PED = (需求量变动的百分比) / (价格变动的百分比)

If PED > 1, demand is price elastic. A small price change causes a big change in demand. e.g., luxury goods.

如果 PED > 1，需求富有弹性。价格小幅变动会引起需求量大幅变动。例如奢侈品。
If PED < 1, demand is price inelastic. A price change has little effect on quantity demanded. e.g., essential goods like bread or medicine.

如果 PED < 1，需求缺乏弹性。价格变动对需求量影响很小。例如面包或药品等必需品。
If PED = 1, demand is unit elastic. The percentage change in quantity demanded is exactly equal to the percentage change in price.

如果 PED = 1，需求为单位弹性。需求量变动的百分比恰好等于价格变动的百分比。

8. Market Structures Overview | 市场结构概述

An industry can be described by the number of firms in it, the type of product they sell, and how easy it is to enter or leave the market. These characteristics define the market structure.

一个行业可以通过其中企业的数量、它们所售产品的类型以及进出市场的难易程度来描述。这些特征定义了市场结构。

Structure 结构	Key Features 主要特征	Real-world Example 实例
Perfect Competition 完全竞争	Many small firms, identical products, no barriers to entry. Firms are ‘price-takers’. 众多小企业，同质产品，无进入壁垒。企业是“价格接受者”。	Agricultural markets (e.g., rice, wheat) 农产品市场（如大米、小麦）
Monopoly 垄断	One dominant firm, unique product, very high barriers to entry. The firm is a ‘price-maker’. 单一主导企业，无相近替代品，极高进入壁垒。企业是“价格制定者”。	Local water utility company 地方自来水公司
Oligopoly 寡头垄断	A few large firms, products can be differentiated or similar, significant entry barriers. Firms are interdependent. 少数几家大企业，产品可有差异或相似，存在明显进入壁垒。企业之间相互依赖。	Supermarket chains, mobile phone networks 连锁超市、移动通信网络

9. Functions of Money | 货币的职能

For money to be effective, it must perform four core functions in an economy. This concept helps distinguish money from simple barter systems.

货币要有效运行，必须在经济中履行四项核心职能。这一概念有助于将货币与简单的物物交换系统区分开来。

Medium of Exchange: It is widely accepted as a method of payment for goods and services, eliminating the need for a double coincidence of wants.

交换媒介：被普遍接受为商品和服务的支付方式，消除了需求的双重耦合。
Unit of Account: It provides a standardised measure for stating and comparing the value of items. Prices are all expressed in the same units.

计价单位：为表示和比较物品价值提供了标准化尺度。所有价格都用同一单位表示。
Store of Value: It can be saved and retrieved at a later time, retaining its purchasing power relatively well over the short term.

价值储藏：可以被储存并在以后取回，在短期内较好地保持其购买力。
Standard of Deferred Payment: It allows debts and future payments to be expressed and settled in money terms, such as loan agreements and mortgages.

延期支付标准：允许债务和未来支付通过货币来表达和结算，例如贷款合同和抵押贷款。

10. Specialization and the Division of Labour | 专业化与劳动分工

Specialisation occurs when individuals, firms, regions, or nations concentrate on producing a narrow range of goods or services. The division of labour breaks a production process down into separate, repetitive tasks performed by different workers.

专业化是指个人、企业、地区或国家集中生产少数商品或服务。劳动分工则是将生产过程分解为不同的重复性任务，交由不同工人完成。

Theorem of Productivity: Specialisation raises productivity (output per worker per hour) because workers become faster, more skilled, and do not waste time switching between tasks. Mechanisation becomes easier.

生产力定理：专业化提高生产力（每小时每名工人的产出），因为工人变得更熟练、更快速，且不会在切换任务上浪费时间。机械化也更容易实现。

However, a drawback is that workers may become bored doing repetitive tasks, and the production process can come to a halt if one specialised segment breaks down. The system also makes countries highly interdependent.

然而，其缺点是工人可能因重复性工作产生厌倦，一旦某个专业环节出现问题，整个生产流程可能停滞。这种体系也使国家之间高度相互依赖。

11. Economic Systems | 经济体系

Every economy must answer the three basic questions of what, how, and for whom to produce. The way they answer these questions determines their economic system. There are three main types.

每个经济体都必须回答生产什么、如何生产、为谁生产这三个基本问题。回答这些问题的方式决定了其经济体系。主要有三种类型。

System 体系	Resource Ownership & Decision-making 资源所有与决策	Key Driver 主要驱动力
Market Economy 市场经济	Private individuals and firms own resources. Decisions are based on the price mechanism (supply and demand). 资源和决策由个人和企业通过价格机制（供给与需求）主导。	Profit motive and consumer sovereignty 利润动机与消费者主权
Command Economy 计划经济	The government owns all resources. Central planners make all output and distribution decisions. 政府拥有所有资源，中央计划机构做出所有生产和分配决策。	Government directives and public interest 政府指令与公共利益
Mixed Economy 混合经济	A blend of private enterprise and government intervention. Most real-world economies are mixed. 私营企业与政府干预相结合。現實世界中大多數经济屬此类。	Both market forces and government regulation 市场力量与政府监管兼而有之

12. Business Costs, Revenue, and Profit | 企业成本、收入与利润

Firms use the following basic formulas to calculate their financial performance. These are core to understanding how businesses make decisions upon profit maximisation goals.

企业使用以下基本公式计算财务表现。这是理解企业如何基于利润最大化目标做出决策的核心。

Total Revenue (TR) = Price (P) x Quantity Sold (Q)

总收入 (TR) = 价格 (P) x 销售数量 (Q)

Total Cost (TC) = Fixed Cost (FC) + Variable Cost (VC)

总成本 (TC) = 固定成本 (FC) + 变动成本 (VC)

Fixed Costs (FC): Costs that do not change with the level of output. e.g., rent, insurance premiums.

固定成本 (FC)：不随产量水平变化的成本。例如租金、保险费。
Variable Costs (VC): Costs that vary directly with output. e.g., raw materials, packaging.

变动成本 (VC)：直接随产量变动的成本。例如原材料、包装。

Profit ( pi ) = Total Revenue (TR) – Total Cost (TC)

利润 ( pi ) = 总收入 (TR) – 总成本 (TC)

A firm earns a profit when TR > TC, a normal profit when TR = TC, and a loss when TR < TC. Profit maximisation is assumed to be the primary objective of most private-sector firms.

当 TR > TC 时企业盈利，当 TR = TC 时为正常利润，当 TR < TC 时为亏损。利润最大化被假设为大多数私营企业的主要目标。

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CIE Year 7 Economics Formula & Theorem Quick Reference Handbook | CIE 7年级经济公式定理速查手册