📚 Year 7 WJEC Business: Formulas & Theorems Quick-Reference Handbook | Year 7 WJEC 商务：公式定理速查手册
Welcome to your handy quick-reference guide for Year 7 WJEC Business. This handbook brings together the essential formulas and core theorems you will encounter during your first year of business studies. Understanding these basics will help you calculate profits, analyse costs, and grasp the fundamental principles that shape business decisions.
欢迎使用你的 Year 7 WJEC 商务实用速查手册。本手册汇集了你在商务学习第一年将要遇到的重要公式和核心定理。掌握这些基础知识将帮助你计算利润、分析成本，并理解影响商业决策的基本原理。
1. Revenue Formula | 收入公式
Revenue is the total amount of money a business receives from selling its goods or services before any costs are deducted. It is sometimes called sales revenue or turnover.
收入是企业在扣除任何成本之前通过销售商品或服务获得的总金额，有时也称作销售收入或营业额。
The revenue formula is:
收入公式为：
Revenue = Selling Price per Unit × Quantity Sold
For example, if a baker sells 200 loaves of bread at £1.20 each, revenue = 1.20 × 200 = £240.
例如，如果一位面包师以每只 1.20 英镑的价格售出 200 条面包，收入 = 1.20 × 200 = 240 英镑。
Businesses aim to increase revenue by raising prices or selling more products, but they must consider what customers are willing to pay.
企业力求通过提高价格或销售更多产品来增加收入，但必须考虑顾客愿意支付的价格。
2. Total Cost Formula | 总成本公式
Total cost refers to all the expenses a business incurs to produce and sell its products. It is the sum of fixed costs and variable costs.
总成本是指企业生产和销售产品所发生的全部费用，是固定成本和可变成本之和。
Total Cost = Fixed Costs + Variable Costs
Fixed costs do not change with the level of output, such as rent, insurance, and permanent staff salaries. Variable costs change directly with output, such as raw materials, packaging, and piece-rate wages.
固定成本不随产量变化，例如租金、保险和长期员工工资。可变成本随产量直接变化，例如原材料、包装和计件工资。
Knowing the difference between fixed and variable costs helps a business plan budgets and set prices that cover all expenses.
了解固定成本和可变成本的区别有助于企业规划预算并制定能够覆盖所有支出的价格。
3. Profit Formula | 利润公式
Profit is the financial reward for taking a business risk. It shows how much money the business keeps after paying all its costs. Businesses need to make a profit to survive and grow.
利润是承担商业风险的经济回报，表明企业在支付所有成本后留存了多少钱。企业需要盈利才能生存和发展。
Profit = Total Revenue − Total Cost
If a market stall has total revenue of £800 and total costs of £620, the profit is £180. If total costs exceed total revenue, the result is a loss.
如果一个小摊位的总收入为 800 英镑，总成本为 620 英镑，则利润为 180 英镑。如果总成本超过总收入，结果就是亏损。
4. Unit Cost Formula | 单位成本公式
Unit cost, also called average cost, tells the business how much it costs to produce one single unit of output. This is useful when comparing production efficiency.
单位成本，也称平均成本，告诉企业生产一个单位的产品需要多少成本，在比较生产效率时非常有用。
Unit Cost = Total Cost ÷ Quantity Produced
If total cost is £4,800 and 1,200 units are produced, the unit cost is £4 per unit. Lowering the unit cost can increase profit margins.
如果总成本为 4,800 英镑，生产了 1,200 个单位，那么单位成本是 4 英镑/单位。降低单位成本可以提高利润率。
5. Contribution per Unit Formula | 单位贡献公式
Contribution per unit shows how much each product sold contributes towards covering fixed costs and then making a profit. It is a key concept for break-even analysis.
单位贡献显示每售出一件产品能为覆盖固定成本并创造利润贡献多少，是盈亏平衡分析的关键概念。
Contribution per Unit = Selling Price per Unit − Variable Cost per Unit
If a candle sells for £5.00 and the variable costs (wax, wick, packaging) are £2.00, the contribution per unit is £3.00. This £3.00 first goes towards paying fixed costs.
如果一支蜡烛售价 5.00 英镑，可变成本（蜡、烛芯、包装）为 2.00 英镑，单位贡献为 3.00 英镑。这 3.00 英镑首先用于支付固定成本。
6. Break-Even Point Formula | 盈亏平衡点公式
The break-even point is the level of sales where total revenue equals total cost, so the business makes neither a profit nor a loss. It is expressed in units or in sales value.
盈亏平衡点是指总收入等于总成本的销售额水平，此时企业既无利润也无亏损，可以用销售量或销售额表示。
Break-Even Point (units) = Fixed Costs ÷ Contribution per Unit
If fixed costs are £3,000 and contribution per unit is £6, the break-even output is 500 units. Selling more than 500 units means the business starts earning a profit.
如果固定成本为 3,000 英镑，单位贡献为 6 英镑，则盈亏平衡产量为 500 单位。销售量超过 500 单位意味着企业开始盈利。
7. Simple Interest Formula | 单利利息公式
Simple interest is the extra money earned on savings or paid on a loan, calculated only on the original principal. It does not consider interest earned on interest.
单利是在储蓄或借入的本金基础上计算出的额外金额，仅按原始本金计算，不涉及复利。
Simple Interest = Principal × Interest Rate × Time
For example, £150 saved at 4% simple annual interest for 5 years earns £150 × 0.04 × 5 = £30 interest. The total amount after 5 years is £180.
例如，150 英镑按 4% 的年单利利率储蓄 5 年，利息 = 150 × 0.04 × 5 = 30 英镑，5 年后总金额为 180 英镑。
8. Percentage Change Formula | 百分比变化公式
Percentage change measures how much a value has increased or decreased compared to the original amount. It is widely used to compare profits, revenues or costs over time.
百分比变化衡量某一数值相对原始金额增减了多少，广泛用于比较一段时间内的利润、收入或成本。
Percentage Change = [(New Value − Original Value) ÷ Original Value] × 100
If a company’s monthly revenue went from £2,500 to £3,000, the percentage increase is [(3000 − 2500) ÷ 2500] × 100 = 20%. A decrease would produce a negative result.
如果一家公司的月收入从 2,500 英镑上升到 3,000 英镑，增长百分比 = [(3000 − 2500) ÷ 2500] × 100 = 20%。减少会得出负值。
9. Opportunity Cost Principle | 机会成本原理
Opportunity cost is the value of the next best alternative that is given up when a choice is made. Every business decision involves an opportunity cost because resources are limited.
机会成本是当做出选择时所放弃的次优替代品的价值。由于资源有限，每一个商业决策都涉及机会成本。
For instance, if an entrepreneur decides to spend £5,000 on new equipment instead of a marketing campaign, the opportunity cost of the equipment is the potential extra sales the campaign could have generated.
例如，如果一位创业者决定用 5,000 英镑购买新设备而不是开展营销活动，那么设备的机会成本就是该营销活动本可能带来的额外销售额。
Understanding opportunity cost helps businesses evaluate trade-offs and use scarce resources wisely.
理解机会成本有助于企业评估权衡并明智地使用稀缺资源。
10. Law of Demand | 需求定律
The law of demand states that, all else being equal, when the price of a product rises, the quantity demanded falls, and when the price falls, the quantity demanded increases.
需求定律指出，在其他条件不变的情况下，当产品价格上涨时，需求量下降；当价格下跌时，需求量增加。
This inverse relationship is a cornerstone of market economies and helps a business predict how many items customers will buy at different price points.
这种反向关系是市场经济的基石，帮助企业预测顾客在不同价位愿意购买的数量。
11. Law of Supply | 供给定律
The law of supply indicates that, all else being equal, when the price of a product rises, the quantity supplied increases, because producers are more willing to supply more to earn higher revenue.
供给定律表明，在其他条件不变的情况下，当产品价格上涨时，供给量增加，因为生产者更愿意提供更多产品以获得更高收入。
When the price is low, suppliers reduce output as it may not cover their costs. This law helps explain production and market behaviour.
当价格较低时，供应商会减少产出，因为可能无法覆盖成本。这一定律有助于解释生产和市场行为。
12. Scarcity and the Economic Problem | 稀缺性与经济问题
Scarcity means there are limited resources to satisfy unlimited human wants. This fundamental economic problem forces businesses and individuals to make choices about how to use land, labour, capital and enterprise.
稀缺性意味着有限的资源无法满足无限的人类需求。这一根本经济问题迫使企业和个人必须就如何使用土地、劳动力、资本和企业家才能做出选择。
The three basic economic questions arising from scarcity are: What to produce? How to produce? For whom to produce? Every business must answer these questions when planning its operations.
源于稀缺性的三个基本经济问题是：生产什么？如何生产？为谁生产？每个企业在规划运营时都必须回答这些问题。
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