📚 GCSE AQA Economics: Formula Summary Handbook | GCSE AQA 经济：公式汇总手册
Mastering the essential formulas in GCSE AQA Economics is crucial for exam success. This handbook compiles every key formula you need—from revenue and costs to elasticity and macroeconomic indicators. Whether you are calculating profit margins, interpreting break-even points, or evaluating elasticity values, these formulas will form the backbone of your analytical skills. Keep this guide handy for quick revision and practice.
掌握 GCSE AQA 经济学中的核心公式是考试成功的关键。本手册汇总了你需要的所有重要公式——从收入与成本到弹性和宏观经济指标。无论是计算利润率、解读盈亏平衡点，还是评估弹性数值，这些公式将构成你分析能力的基石。请收藏本指南，以便快速复习与练习。
1. Revenue | 收入
Total Revenue (TR) is the income a business generates from selling its goods or services. It is found by multiplying the selling price per unit (P) by the quantity sold (Q).
总收入（TR）是企业通过销售商品或服务所获得的收入。它由单价（P）乘以销售数量（Q）计算得出。
TR = P x Q
Average Revenue (AR) shows the revenue earned per unit sold. It is calculated by dividing total revenue by the quantity sold. When a firm charges the same price for all units, AR equals price.
平均收入（AR）表示每售出一单位商品所获得的收入。它通过总收入除以销售数量计算。当企业对所有单位收取相同价格时，平均收入等于价格。
AR = TR / Q = P
A drop in price will raise quantity demanded but the total revenue effect depends on price elasticity of demand (covered later). Students must be able to calculate TR and AR from sales data.
降价会提高需求量，但对总收入的影响取决于需求价格弹性（后文介绍）。学生必须能够根据销售数据计算 TR 和 AR。
2. Costs | 成本
Total costs (TC) are the sum of all expenses a firm incurs to produce its output. They are split into total fixed costs (TFC), which do not vary with output, and total variable costs (TVC), which rise as output increases.
总成本（TC）是企业为生产产出所发生的全部费用之和。它分为不随产出变动的总固定成本（TFC）和随产出增加而上升的总变动成本（TVC）。
TC = TFC + TVC
Average costs are used to show the cost per unit. Average fixed cost (AFC) is total fixed cost divided by quantity. Average variable cost (AVC) is total variable cost divided by quantity. Average total cost (ATC) can be found by dividing total cost by output, or by adding AFC and AVC.
平均成本用于表示单位成本。平均固定成本（AFC）等于总固定成本除以产量。平均变动成本（AVC）等于总变动成本除以产量。平均总成本（ATC）可以通过总成本除以产量获得，也可通过 AFC 加 AVC 得到。
AFC = TFC / Q
AVC = TVC / Q
ATC = TC / Q = AFC + AVC
Understanding these cost structures helps firms decide on production levels and pricing strategies. A simple table often illustrates how AFC falls as output spreads fixed costs, while AVC may initially fall then rise due to diminishing returns.
理解这些成本结构有助于企业决定生产水平和定价策略。一个简单的表格常用来展示随着产量增加，AFC 因固定成本摊薄而下降，而 AVC 可能因边际回报递减先降后升。
3. Profit and Profit Margin | 利润与利润率
Profit is the reward for taking a business risk. It is found by subtracting total costs from total revenue. A negative value signals a loss.
利润是承担商业风险的回报，通过总收入减去总成本得出。负值表示亏损。
Profit = TR – TC
Profit margin (or net profit margin) expresses profit as a percentage of revenue, indicating how much of each pound of sales is retained as profit. It is a key measure of profitability.
利润率（或净利率）将利润表示为收入的百分比，显示每英镑销售收入中有多少留存为利润。它是衡量盈利能力的关键指标。
Profit Margin = (Profit / Revenue) x 100%
For example, if a firm earns £50,000 in revenue and has £38,000 in total costs, profit is £12,000, giving a profit margin of 24%. Comparing margins over time or across competitors helps assess efficiency.
例如，某企业收入为 50,000 英镑，总成本为 38,000 英镑，则利润为 12,000 英镑，利润率为 24%。比较不同时期或竞争对手的利润率有助于评估效率。
4. Break-even Analysis | 盈亏平衡分析
The break-even point is the output level where total revenue equals total costs, so the firm makes neither a profit nor a loss. The formula uses contribution per unit, which is the selling price minus average variable cost.
盈亏平衡点是指总收入等于总成本时的产量水平，此时企业既不盈利也不亏损。该公式使用单位贡献毛利，即售价减去平均变动成本。
Break-even Output = TFC / (Price – AVC)
Contribution per unit (Price – AVC) shows how much each sale contributes towards covering fixed costs. Once fixed costs are covered, further sales generate profit.
单位贡献毛利（价格 – AVC）表示每笔销售中有多少用于冲抵固定成本。一旦固定成本被覆盖，额外销售便产生利润。
A business can also use this analysis to find the output needed to achieve a target profit by adding the desired profit figure to TFC in the numerator: (TFC + Target Profit) / (Price – AVC).
企业也可以将此分析用于目标利润产出：分子加上目标利润，即 (TFC + 目标利润) / (价格 – AVC)。
5. Price Elasticity of Demand (PED) | 需求价格弹性
PED measures the responsiveness of quantity demanded to a change in price. It is calculated as the percentage change in quantity demanded divided by the percentage change in price.
PED 衡量需求量对价格变化的反应程度。计算公式为需求量变动百分比除以价格变动百分比。
PED = %Change in Qd / %Change in P
To find percentage changes, use the formula: (New value – Original value) / Original value x 100. If PED > 1, demand is price elastic; if PED < 1, it is price inelastic; if PED = 1, it is unit elastic.
计算百分比变化使用公式：（新数值 – 原始数值）/ 原始数值 x 100。若 PED > 1，需求富有价格弹性；若 PED < 1，需求缺乏价格弹性；若 PED = 1，则为单位弹性。
Firms use PED to predict the impact of price changes on total revenue. With elastic demand, a price cut raises total revenue; with inelastic demand, a price cut lowers it.
企业利用 PED 预测价格变动对总收入的影响。需求富有弹性时，降价增加总收入；缺乏弹性时，降价减少总收入。
6. Income Elasticity of Demand (YED) | 需求收入弹性
YED measures how quantity demanded reacts to a change in consumer income. It is the percentage change in quantity demanded divided by the percentage change in income.
YED 衡量需求量如何对消费者收入变化做出反应。其为需求量变动百分比除以收入变动百分比。
YED = %Change in Qd / %Change in Income (Y)
Goods with positive YED are normal goods; those with negative YED are inferior goods. A YED greater than 1 identifies luxury goods, while a positive YED less than 1 indicates necessities.
YED 为正的商品是正常品；YED 为负的是低档品。YED 大于 1 代表奢侈品，而正但小于 1 的 YED 代表必需品。
Calculating YED helps firms forecast demand as the economy grows or shrinks. For example, during a recession, demand for inferior goods may increase.
计算 YED 有助于企业在经济扩张或紧缩时预测需求。例如，在经济衰退期，低档品的需求可能增加。
7. Price Elasticity of Supply (PES) | 供给价格弹性
PES shows how responsive quantity supplied is to a change in price. Its formula mirrors that of PED, using quantity supplied instead of quantity demanded.
PES 表示供给量对价格变化的反应程度。其公式与 PED 类似，只是使用供给量而非需求量。
PES = %Change in Qs / %Change in P
A PES value greater than 1 indicates supply is elastic, meaning producers can increase output quickly when prices rise. A PES less than 1 indicates inelastic supply, often due to capacity limits or lengthy production times.
PES 值大于 1 表示供给富有弹性，即价格上涨时生产者能迅速增加产量。PES 小于 1 表示供给缺乏弹性，通常是受产能限制或生产周期长的影响。
Agricultural goods frequently have low PES in the short run because growing cycles cannot easily be sped up. Understanding PES helps explain volatile commodity prices.
农产品在短期内通常具有较低的 PES，因为生长周期难以轻易加速。理解 PES 有助于解释大宗商品价格的波动性。
8. Marginal Cost and Average Cost in Depth | 深入理解边际成本与平均成本
While average cost tells us the cost per unit at a given output, marginal cost (MC) focuses on the extra cost of producing one additional unit. It is the change in total cost divided by the change in output.
平均成本显示了某一产量下的单位成本，而边际成本（MC）关注生产额外一单位产品所带来的新增成本。它等于总成本的变化量除以产量的变化量。
MC = Change in TC (DeltaTC) / Change in Q (DeltaQ)
When marginal cost is below average total cost, ATC falls; when MC is above ATC, ATC rises. This relationship creates the characteristic U-shaped average cost curve.
当边际成本低于平均总成本时，ATC 下降；当 MC 高于 ATC 时，ATC 上升。这一关系形成了典型的 U 形平均成本曲线。
Worked example: if total cost rises from £800 to £860 when output increases from 50 to 52 units, then DeltaTC = £60, DeltaQ = 2, so MC = £30. At the same point, if TC = £800, ATC = £800/50 = £16. The rising MC will eventually pull ATC up.
计算示例：若产量从 50 单位增至 52 单位时，总成本从 800 英镑升至 860 英镑，则 DeltaTC = 60 英镑，DeltaQ = 2，MC = 30 英镑。在该产量点上，若 TC = 800 英镑，ATC = 800/50 = 16 英镑。逐渐上升的 MC 最终将拉高 ATC。
9. Productivity and Unit Costs | 生产率与单位成本
Labour productivity measures the efficiency of a workforce. It is typically expressed as output per worker over a given period.
劳动生产率衡量劳动力的效率，通常表示为每名工人在特定时期内的产出。
Labour Productivity = Total Output / Number of Workers
Higher productivity reduces unit labour costs, making a business more competitive. Another useful metric is unit cost (also called average cost per unit), which is simply total cost divided by total output.
更高的生产率会降低单位劳动力成本，增强企业竞争力。另一个实用指标是单位成本（也称平均单位成本），即总成本除以总产出。
Unit Cost = Total Cost / Total Output
Although unit cost is conceptually identical to ATC, the term is often used when discussing operational efficiency. Managers track both productivity and unit cost to identify waste and set improvement targets.
尽管单位成本在概念上与 ATC 相同，但在讨论运营效率时常使用这一术语。管理者同时追踪生产率和单位成本，以发现浪费并设定改进目标。
10. Macroeconomic Formulas | 宏观经济公式
Macroeconomic indicators bring aggregate data into calculations. GDP per capita, for example, divides a country’s total gross domestic product by its population to give an average income measure.
宏观经济指标将总量数据引入计算。例如，人均 GDP 通过将一个国家的国内生产总值除以其人口得出平均收入指标。
GDP per Capita = GDP / Population
Inflation rate measures the percentage increase in the general price level. Using a consumer price index (CPI), it is calculated as the change in the index divided by the original index value, then multiplied by 100.
通货膨胀率衡量总体物价水平的百分比上涨。使用消费者价格指数（CPI），其计算公式为指数变动量除以基期指数值，再乘以 100。
Inflation Rate = (CPI new – CPI old) / CPI old x 100%
The unemployment rate expresses the proportion of the labour force that is actively seeking work but unable to find employment.
失业率表示劳动力中积极寻找工作但未能就业的人口比例。
Unemployment Rate = (Number of Unemployed / Labour Force) x 100%
For international trade, currency conversions use exchange rates. To convert an amount from the home currency to a foreign currency when the rate is quoted as the foreign currency per unit of home currency (e.g. 1 GBP = 1.30 USD), multiply the home currency amount by the exchange rate.
在国际贸易中，货币兑换使用汇率。若汇率报价为每单位本币可兑换的外币数量（例如 1 英镑 = 1.30 美元），则将本币金额乘以汇率即可换算为外币金额。
Amount in Foreign Currency = Amount in Home Currency x Exchange Rate
These formulas provide a foundation for analysing an economy’s performance and comparing living standards across nations.
这些公式为分析经济表现和比较各国生活水平奠定了基础。
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