📚 Year 8 CCEA Economics: Key Formulas & Theorems Quick Reference Guide | Year 8 CCEA 经济：公式定理速查手册
This quick reference guide compiles the essential formulas, definitions, and key theorems from the Year 8 CCEA Economics curriculum. It is designed to help you revise core concepts such as scarcity, opportunity cost, market equilibrium, business costs, and personal finance calculations. Use this handbook to reinforce your understanding and build confidence before assessments.
本速查手册汇编了 Year 8 CCEA 经济课程中的重要公式、定义和关键定理。手册旨在帮助你复习稀缺性、机会成本、市场均衡、企业成本以及个人理财计算等核心概念。使用本手册巩固理解，并在评估前建立信心。
1. Scarcity and Choice | 稀缺性与选择
The basic economic problem arises because resources are limited while human wants are unlimited. Scarcity forces individuals, businesses, and governments to make choices about how to allocate resources efficiently.
基本的经济问题源于资源有限而人类的欲望无限。稀缺性迫使个人、企业和政府就如何有效配置资源做出选择。
2. Opportunity Cost | 机会成本
Opportunity cost is the value of the next best alternative forgone when a choice is made. It can be expressed as:
机会成本是指做出选择时所放弃的次优选项的价值。它可以表示为：
Opportunity Cost = Return on best forgone option − Return on chosen option
机会成本 = 放弃的最佳选项的收益 − 所选选项的收益
3. Production Possibility Frontier (PPF) | 生产可能性边界
The PPF shows the maximum possible output combinations of two goods an economy can produce with given resources and technology. Points on the curve represent efficient production; points inside indicate inefficient use of resources; points outside are unattainable with current resources.
生产可能性边界展示了一个经济体在给定资源和技术条件下能够生产的两种商品的最大可能产量组合。曲线上的点代表有效率的生产；曲线内部的点表示资源未得到有效利用；曲线外部的点在当前资源下无法达到。
Movement along a PPF shows the trade-off between the two goods; the opportunity cost of producing more of one good is the quantity of the other good that must be given up.
沿生产可能性边界的移动显示了两种商品之间的权衡；多生产一种商品的机会成本是必须放弃的另一种商品的数量。
4. Law of Demand | 需求定律
The law of demand states that, ceteris paribus, as the price of a good increases, the quantity demanded decreases, and vice versa. There is an inverse relationship between price and quantity demanded.
需求定律指出，在其他条件不变的情况下，商品价格上升，需求量下降；价格下降，需求量上升。价格与需求量之间存在反向关系。
The demand curve slopes downwards from left to right, reflecting this inverse relationship.
需求曲线从左向右下方倾斜，反映了这种反向关系。
5. Law of Supply | 供给定律
The law of supply states that, ceteris paribus, as the price of a good increases, the quantity supplied increases, and vice versa. There is a direct (positive) relationship between price and quantity supplied.
供给定律指出，在其他条件不变的情况下，商品价格上升，供给量上升；价格下降，供给量下降。价格与供给量之间存在正向（正比例）关系。
The supply curve slopes upwards from left to right, showing that producers are willing to supply more at higher prices.
供给曲线从左向右上方倾斜，表明生产者在较高价格下愿意供给更多。
6. Market Equilibrium | 市场均衡
Market equilibrium occurs at the price where quantity demanded equals quantity supplied. It is the point where the demand and supply curves intersect. At any price above equilibrium, there is excess supply (surplus); below equilibrium, there is excess demand (shortage).
市场均衡发生在需求量等于供给量的价格水平上。这是需求曲线与供给曲线相交的点。在任何高于均衡价格的价格水平上，存在超额供给（过剩）；低于均衡价格时，存在超额需求（短缺）。
The equilibrium price and quantity are determined by the interaction of demand and supply.
均衡价格和均衡数量由需求与供给的相互作用决定。
7. Total Revenue, Total Cost, and Profit | 总收益、总成本与利润
These basic business formulas are essential for understanding firm behaviour:
这些基本的企业公式对于理解企业行为至关重要：
Total Revenue (TR) = Price (P) × Quantity Sold (Q)
总收益 (TR) = 价格 (P) × 销售量 (Q)
Total Cost (TC) = Fixed Costs + Variable Costs
总成本 (TC) = 固定成本 + 可变成本
Profit = Total Revenue − Total Cost
利润 = 总收益 − 总成本
If total revenue is greater than total cost, the firm makes a profit. If total cost exceeds total revenue, the firm makes a loss.
如果总收益大于总成本，企业获得利润。如果总成本超过总收益，企业发生亏损。
8. Average Cost | 平均成本
Average cost (or unit cost) is calculated by dividing total cost by the quantity of output produced. It helps businesses determine efficiency and set prices.
平均成本（或单位成本）通过总成本除以产出数量来计算。它帮助企业确定效率和制定价格。
Average Cost (AC) = Total Cost (TC) ÷ Quantity (Q)
平均成本 (AC) = 总成本 (TC) ÷ 数量 (Q)
When average cost falls as output rises, the firm may benefit from economies of scale; when average cost rises, diseconomies of scale may occur.
当产出增加而平均成本下降时，企业可能受益于规模经济；当平均成本上升时，可能出现规模不经济。
9. Simple Interest | 单利
Simple interest is a way of calculating the cost of borrowing money or the return on savings, where interest is paid only on the original principal amount.
单利是一种计算借款成本或储蓄收益的方法，其利息仅根据原始本金计算。
Simple Interest (SI) = Principal (P) × Rate (r) × Time (t)
单利 (SI) = 本金 (P) × 年利率 (r) × 时间 (t)
In this formula, r is the annual interest rate expressed as a decimal (e.g., 5% = 0.05), and t is the number of years.
在该公式中，r 是以小数表示的年利率（例如 5% = 0.05），t 是年数。
For savings, the total amount after t years can be found by: Amount = Principal + Simple Interest. For borrowing, the total repayment is the sum of the principal and the simple interest charged.
对于储蓄，t 年后的总金额可以通过以下公式计算：总额 = 本金 + 单利。对于借款，总还款额是本金与所收取单利的总和。
10. Functions of Money | 货币的功能
Money serves four key functions in an economy. These functions make trade and economic activity much easier than barter.
货币在经济中发挥四个关键功能。这些功能使贸易和经济活动比物物交换容易得多。
Medium of exchange: Money is widely accepted as payment for goods and services, removing the need for a double coincidence of wants.
交换媒介：货币被广泛接受作为商品和服务的支付手段，消除了对欲望双重巧合的需要。
Unit of account: Money provides a common measure of the value of different goods and services, making it simple to compare prices.
计价单位：货币为不同商品和服务的价值提供了共同的衡量标准，使价格比较变得简单。
Store of value: Money can be saved and used later; its value is maintained over time, although inflation can reduce purchasing power.
价值储藏：货币可以储蓄并在以后使用；其价值可以随时间保持，尽管通货膨胀会降低购买力。
Standard of deferred payment: Money allows people to lend and borrow, and to repay debts in the future, as it is a reliable form for future payments.
延期支付标准：货币允许人们进行贷款和借款，并能够在未来偿还债务，因为它是一种可靠的未来支付形式。
Published by TutorHao | 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