The big idea: A population pyramid shows a country's age and sex structure.
- Males are on the left, females on the right. - Age groups are stacked, youngest at the bottom. - Bar length = the share of people in that group.
[Diagram: geo-population-pyramid] - Available in full study mode
Key terms
- Age structure — how the population is split between young, working-age and old.
- Dependants — under-15s and over-65s, who rely on the working-age (15–64) population.
- Sex ratio — the balance of males to females (often per 100 females).
The shape tells the story. Compare the youthful pyramid above with this ageing one — the base is narrow and the top is wide.
[Diagram: geo-population-pyramid] - Available in full study mode
| Shape | What it means |
|---|---|
| Wide base, narrows quickly | Youthful — high birth rate, fast growth (often lower-income) |
| Narrow base, wide middle/top | Ageing — low birth rate, more elderly (often higher-income) |
| A bulge in one band | A past baby boom, or migration of working-age people |
| Longer female side at the top | Women tend to live longer — common in older age groups |
Stop wasting time on topics you know
Our AI identifies your weak areas and focuses your study time where it matters. No more overstudying easy topics.
Natural increase: The rate of natural increase is births minus deaths (per 1000 people per year), ignoring migration.
Positive → the population grows from within; negative → it shrinks.
How this is tested: Paper 2 Q1 almost always opens by making you read a population pyramid or age graph — Identify the biggest group [1], Estimate a value [1], then Describe the shape [2]. Read the axis carefully and quote figures.
[Diagram: geo-population-pyramid] - Available in full study mode
IB-style question — read the pyramid
Using the population pyramid above: (a) identify the age group with the most people [1]; (b) estimate the percentage aged 0–14 [1]; (c) describe the shape of the pyramid [2].
How to answer each part
- (a) Identify the largest group. Find the longest pair of bars — the 0–14 group has the longest bars, so it has the most people.
- (b) Estimate 0–14. Add the male and female bars for 0–14 (≈16% + ≈15%) → about 31%.
- (c) Describe the shape. It has a wide base that narrows quickly toward the top — a youthful population with a high birth rate.
Final answer
(a) the 0–14 group; (b) ≈ 31%; (c) wide base narrowing to a small top → youthful, high birth rate.
Data-response marks: Identify/State = read it straight off. Estimate = give a sensible figure from the axis. Describe = report the pattern (shape + figures), no reasons.