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1 Primary & Middle School Mathematics1–9 年级在线 2 High School Mathematics10–12 年级在线 3 University Mathematics — Year 1本科一年级在线 4 University Mathematics — Year 2本科二年级在线 5 University Mathematics — Year 3本科三年级在线

1 Primary & Middle School Physics1–9 年级在线 2 High School Physics10–12 年级在线 3 University Physics — Year 1本科一年级在线 4 University Physics — Year 2本科二年级在线 5 University Physics — Year 3本科三年级在线

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1 Markets I: The Ecosystem and Exchange-Traded Markets市场在线 2 Markets II: Rates, FX and Credit市场在线 3 Markets III: Commodities, Energy and Crypto市场在线 4 Quantitative Methods方法在线 5 Derivatives and Volatility衍生品在线 6 Rates, Credit, XVA and Risk利率、信用与风险在线 7 Research Craft: Predictors, Backtests, Measurement, Portfolios研究在线 8 Strategies I: Equities and Futures策略在线 9 Strategies II: Volatility, Relative Value, Macro and the Bank Desks策略在线 10 Microstructure and Execution交易执行在线 11 Market Making and High-Frequency Trading做市在线 12 Machine Learning for Markets机器学习在线 13 Low-Latency Software技术在线 14 Networks, Hardware and Trading Infrastructure技术在线 15 Research, Data and Risk Platforms技术在线 16 The Desk and the Firm公司运营在线 17 The Industry: Firms, Roles and Careers职业发展在线 18 Interviews I: Maths, Probability and Speed职业发展在线 19 Interviews II: Markets, Trading Games and the Final Round职业发展在线 20 Interviews III: Code职业发展在线

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Mathematics · 术语表

什么是 Percentage？

Definition 44.6 Primary & Middle School Mathematics · 第 44 章 — Proportionality and Data

“ $t\,\%$ of a quantity” means the fraction $\frac{t}{100}$ of it: $25\,\%$ of $60$ is $\frac{25}{100} \times 60 = 15$ . A percentage is a proportionality with coefficient $\frac{t}{100}$ .

示例

Example 44.7

A class of $30$ students contains $40\,\%$ girls. Number of girls, step by step: $40\,\%$ means $\frac{40}{100} = 0.4$ , and $0.4 \times 30 = 12$ girls. Useful landmarks: $50\,\%$ is one half, $25\,\%$ one quarter, $10\,\%$ one tenth — so $10\,\%$ of $30$ is $3$ , and $40\,\% = 4 \times 10\,\%$ is $4 \times 3 = 12$ : same answer, computed mentally.

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