Population Composition
Introduced| English |
|---|
| population composition/ˌpɒpjʊˈleɪʃn ˌkɒmpəˈzɪʃn/ |
| population pyramid/ˌpɒpjʊˈleɪʃn ˈpɪrəmɪd/ |
| dependency ratio/dɪˈpendənsi ˈreɪʃɪəʊ/ |
The make-up of a population
- Population composition 人口构成 is the make-up of a population by age and sex.
- It is shown on a population pyramid 人口金字塔 — back-to-back bar charts.
- The shape of the pyramid tells you the story of a country.
The make-up of a population by age and sex is population ____.
Population composition is shown on a population pyramid.
Reading the shape
- A wide base = many young people = high birth rate = rapid growth.
- Straight sides = slow, stable growth.
- A narrow base = few young people = an ageing, shrinking population.
What does the pyramid shape mean?
Sort each pyramid shape by what it tells you about growth.
A population pyramid with a very wide base shows...
A wide base = many young people = high birth rate = rapid growth.
Match each pyramid shape to its meaning.
Wide = growing; straight = stable; narrow = ageing.
The dependency ratio
- The dependency ratio 抚养比 compares dependents to working-age people.
- Dependents are the young (under 15) and the old (over 64).
- A high ratio strains the workers who must support everyone else.
The dependency ratio counts the young and the old as dependents.
Dependents = under 15 and over 64; the working-age support them.
A country has 30 million dependents and 60 million working-age people. What is the dependency ratio, as dependents per 100 workers?
30/60 = 0.5, so 50 dependents per 100 workers.
A wide base is not always good. It means rapid growth, which can strain schools, jobs, food, and services. A narrow base is not simply "bad" either — it means an ageing society with its own challenges. Read the shape, do not judge it.
Niger has a wide-based pyramid: about half its people are children. Japan has a narrow-based, top-heavy pyramid: many elderly, few children. Same chart type, opposite stories — one faces rapid growth, the other rapid ageing.
Population composition (age and sex) is shown on a population pyramid. A wide base = rapid growth; straight sides = stable; narrow base = ageing. The dependency ratio compares the young + old to working-age people.