📚 AS Eduqas Geography: Formula and Theorems Quick Reference Guide | AS Eduqas 地理：公式定理速查手册
This quick reference guide compiles all the essential formulas, indices, and statistical tests needed for AS Eduqas Geography. It spans population dynamics, urban hierarchy, hydrological measurements, atmospheric processes, hazard analysis, and fieldwork statistical tools. Each section provides a concise explanation and the mathematical expression, enabling you to apply them accurately in exam responses and independent investigations.
本速查手册汇编了 AS Eduqas 地理所需的所有关键公式、指标和统计检验，涵盖人口动态、城市层级、水文测量、大气过程、灾害分析和实地调查统计工具。每一节都给出简洁说明和数学表达式，帮助你在考试答题和自主探究中准确运用。
1. Population Change Formulas | 人口变化公式
The Crude Birth Rate (CBR) measures the number of live births per 1,000 people in a population per year. The Crude Death Rate (CDR) is the number of deaths per 1,000 people in the same period.
CBR = (B / P) × 1000 CDR = (D / P) × 1000
粗出生率（CBR）体现每年每千人口中的活产婴儿数；粗死亡率（CDR）则是每千人口中的死亡人数。
The rate of natural increase per 1,000 people is obtained by subtracting CDR from CBR. To express this as an annual percentage growth rate, divide the result by 10.
Natural increase (per 1000) = CBR – CDR Growth rate (%) = (CBR – CDR) / 10
每千人中自然增长率等于 CBR 减去 CDR。换算为年增长率百分比时，再除以 10。
Doubling time estimates the number of years needed for a population to double in size, assuming a constant exponential growth rate. The widely used 'Rule of 70' is applied.
Doubling time (years) ≈ 70 / annual growth rate (%)
人口倍增时间估算在固定指数增长率下人口翻倍所需的年数，常用“70法则”，即 70 除以年增长率（%）。
Net migration rate captures the balance between immigration (I) and emigration (E) per 1,000 population, giving a clearer picture of overall population change.
Net migration rate = ((I – E) / P) × 1000
净迁移率捕捉每千人中迁入（I）与迁出（E）之差，更清晰地反映总人口变动。
2. Urban Primacy and the Rank-Size Rule | 城市首位度与位序-规模法则
The two-city primacy index compares the population of the largest city (P₁) to that of the second largest city (P₂). A value above 2 usually signals strong urban primacy.
2-city index = P₁ / P₂
双城首位度指数将最大城市人口（P₁）与第二大城市人口（P₂）比较。数值大于 2 通常意味着明显的首位分布。
The four-city index compares the largest city to the combined population of the next three largest cities, offering a broader measure of dominance.
4-city index = P₁ / (P₂ + P₃ + P₄)
四城市指数将最大城市与随后的三大城市总人口比较，能更综合地衡量核心城市的支配程度。大于 1 表明强首位度。
According to the rank-size rule, the population of the nth-ranking city (Pₙ) is approximately the population of the largest city divided by its rank. This pattern is typical in many developed countries.
Pₙ = P₁ / n
位序-规模法则认为，第 n 位城市的人口（Pₙ）约等于最大城市人口除以其位序。许多发达国家符合这一模式。
3. Dependency Ratio | 依赖比率
The total dependency ratio expresses the proportion of non-working-age population (those under 15 and over 64) relative to the working-age population (15–64). It is a key indicator of the economic burden on the productive segment of society.
Total Dependency Ratio = ((Pop₀–₁₄ + Pop₆₅₊) / Pop₁₅–₆₄) × 100
总依赖比率体现非
Published by TutorHao | AS Geography 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