CBSE Class 8 · Dynamics of Population

Population Composition, Pyramids and the Demographic Dividend: Class 8 Notes and Questions

Updated 17 October 2026 · Fact-checked

Population composition means the age, sex and other features of a population. The sex ratio is the number of females per 1,000 males (India: 933 in 2001, 943 in 2011). A population pyramid shows age and sex groups; India's has moved from a wide-based triangle to a bell shape. India's large working-age group gives a demographic dividend, but the window is limited because ageing will set in after 2050.

Notice the pyramid changes from a wide base of children to a bulging middle of working-age adults, a demographic dividend that lasts only until ageing after 205

Illustration drawn for QuestionBuddy.

Understand Population Composition, Pyramids and the Demographic Dividend

Structure or composition of population. Characteristics such as age, gender, occupation and education. The working-age population is described as people aged 15 to 64 who are most productive. India's distribution (Fig. 6.13): Uttar Pradesh has about 16 per cent of the population, Maharashtra and Bihar about 9 per cent each, West Bengal about 8 per cent.

Sex ratio. The number of females per 1,000 males; an indicator of gender balance that reflects socio-economic and cultural dynamics. In Census 2001 India's sex ratio was 933; in Census 2011 it improved to 943, and women formed 48.5 per cent of the population. A balanced ratio matters for equitable development and social stability. Some states (Kerala, Puducherry, Tamil Nadu) had ratios above or near 1,000.

Population pyramid (population structure diagram). A graph of the number of people by age group and gender: the bottom shows the young, the middle adults and the top the elderly. A wide base means many births, a young, growing population (like India or Nigeria earlier); a widest middle means mostly working-age adults; a wide top means an ageing population (like Japan). It is shaped like a pyramid when there are more young people at the bottom and fewer old people at the top. NCERT notes the diagram is really a 2-D picture of a 3-D idea and may look like a triangle or a bell.

India's changing pyramid. In the 1950s it was a narrow triangle: many children and young people, high birth rate, and low life expectancy of about 30-35 years. In recent years it is bell-shaped: the base has narrowed (smaller families), the middle (working-age) has widened a great deal and the top is slowly widening as people live longer. India has moved from a young, fast-growing population to a more balanced one and may start ageing slowly, like Japan or China.

Demographic dividend. The economic growth potential of a nation arising from a young and productive age structure. About 27 per cent of Indians are under 15 and nearly 65 per cent are of working age (NCERT gives the working-age band as 15-59 years here). Median ages (NCERT's figure): India 28, USA 39, China 40, Germany 47, Italy 48, Japan 50. A youth bulge is a large young population (16 to 30 years), common in Stage 2 countries. More working people means more economic activity, more taxes for schools, hospitals and roads.

Limited window. The number of children under five peaked in 2007 and under-15s in 2011, and are declining; after 2050 the growth in the young population falls and India begins to transition towards an older population. Kerala and Tamil Nadu already show ageing compared to Bihar and Uttar Pradesh.

Challenges of ageing. More elderly people need healthcare and care, while fewer young workers and taxpayers support them; retirement reduces the workforce; governments face pressure on pensions (regular payments to retirees) and services. Older people also contribute wisdom, rituals and stories (ashrama dharma). Policy responses: Japan raised the retirement age, uses technology and automation, community centres, robots and AI assistants for elderly care. Developing countries must invest in education, skilling and health to harness the dividend; women face a double burden of work and home duties, so childcare, daycare and flexible hours help. Policies to revive fertility have not been very successful so far.

Population Composition, Pyramids and the Demographic Dividend: key facts

Sex ratio: Females per 1,000 males | number of females / number of males x 1,000; Females per 1,000 males.
India's sex ratio (NCERT): 2001: 933
2011: 943
women 48.5 per cent in 2011; Improved by 10 points.
Pyramid shapes: Wide base young growing population
Wide middle working-age majority
Wide top ageing population; India: triangle (1950s) to bell shape.
India's age shares (NCERT): About 27 per cent under 15 | nearly 65 per cent working age (15-59); Basis of the dividend.
Median age: India 28
USA 39
China 40
Germany 47
Italy 48
Japan 50; Lower median age means a younger population.

Wide base	young growing population
Wide middle	working-age majority
Wide top	ageing population

How to answer Population Composition, Pyramids and the Demographic Dividend questions

Questions ask you to calculate a sex ratio, read a pyramid and infer the population, explain demographic dividend with its condition and limit, and suggest policy for ageing.

1For sex ratio, divide females by males and multiply by 1,000; state the unit as females per 1,000 males.
2To read a pyramid, look at the base, middle and top and name the type of population.
3For dividend, define, give India's numbers and conditions (education, jobs, health) and the 2050 limit.
4For ageing, give three problems and two policy responses.
5Keep derived figures labelled; NCERT's numbers are in the formulas box.

Population Composition, Pyramids and the Demographic Dividend in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Calculating a sex ratio

Suppose a town has 48,000 men and 45,600 women (hypothetical).

Find its sex ratio and compare it with India's 2011 figure.

Try it first, then show the solutionSolution

Sex ratio = females / males x 1,000 = 45,600 / 48,000 x 1,000.
45,600 / 48,000 = 0.95, so the ratio is 950.
Compare: 950 is above 943.

Answer: Sex ratio = 45,600 / 48,000 x 1,000 = 950 females per 1,000 males. This is slightly higher than India's 943 in Census 2011. Check: 48,000 x 0.95 = 45,600.

Memory hook: Females first, per thousand males.

Reading a pyramid

Suppose a country's pyramid has a narrow base and a wide top, with more people aged above 65 than children under 5.

What kind of population is this, and what are two likely needs?

Try it first, then show the solutionSolution

A wide top with a narrow base indicates an ageing population.
This calls for more elderly care and pensions.

Answer: It is an ageing population, like Japan. Such a country needs more healthcare and elder-care services and has to manage pensions with fewer young workers, possibly by raising retirement age or using technology.

Memory hook: Wide top, old country.

Tricks to remember Population Composition, Pyramids and the Demographic Dividend

Short memory aids. Say each one aloud once, then use it on a question the same day.

933 to 943
Sex ratio: 2001 = 933, 2011 = 943.
Use it when: India's sex ratio.
Base-Middle-Top
Base = children, middle = workers, top = elderly.
Use it when: Reading a pyramid.
Dividend window
Under-5s peaked 2007; under-15s 2011; ageing after 2050.
Use it when: Why the dividend is limited.

Population Composition, Pyramids and the Demographic Dividend: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Sex ratio definition · 1 mark · MCQBoard level

Sex ratio is defined as the number of:
(a) males per 1,000 females
(b) females per 1,000 males
(c) females per 100 males
(d) children per 1,000 adults

Try it first, then show the solutionSolution

NCERT: sex ratio is the number of females per 1,000 males (1 mark).

Answer: (b) females per 1,000 males

Example 2: Sex ratio calculation (3 marks) · 3 marks · Short answerHarder board level

In a town of 1,20,000 people there are 62,500 males. Find the number of females, the sex ratio, and say whether it is above or below India's 943 (2011). (3 marks)

Try it first, then show the solutionSolution

Females = 1,20,000 - 62,500 = 57,500 (1 mark).
Sex ratio = 57,500 / 62,500 x 1,000 = 920 (1 mark).
920 is below 943 (1 mark).

Answer: Number of females = 1,20,000 - 62,500 = 57,500. Sex ratio = 57,500 / 62,500 x 1,000 = 920 females per 1,000 males. This is below India's 943 in 2011. Check: 62,500 x 0.92 = 57,500.

Example 3: Assertion-reason: pyramid shape · 1 mark · Assertion-reasonHarder board level

Assertion (A): India's population pyramid has become bell-shaped in recent years.
Reason (R): The base has narrowed as families have fewer children, and the working-age group has widened.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.

Try it first, then show the solutionSolution

NCERT describes exactly these changes as the reason for the shape (1 mark).

Answer: (a) Both A and R are true, and R is the correct explanation of A.

Example 4: Demographic dividend (5 marks) · 5 marks · Long answerHarder board level

What is the demographic dividend? Explain why India's opportunity is described as 'limited' and what must be done to benefit from it. (5 marks)

Try it first, then show the solutionSolution

Definition: economic growth potential arising from a young, productive age structure (1 mark).
India: about 27 per cent under 15 and nearly 65 per cent of working age (1 mark).
More workers mean more output and tax revenue for schools, hospitals and roads (1 mark).
Limited: births and young numbers have peaked (under-5s in 2007, under-15s in 2011); ageing after 2050 (1 mark).
Needs: investment in education, skilling, health and jobs, plus childcare support for working women (1 mark).

Answer: The demographic dividend is the economic growth potential of a country that comes from a young and productive age structure. In India about 27 per cent of the population is under 15 and nearly 65 per cent is of working age, so many people can work in factories, offices and farms or start businesses; more working people mean more economic activity and more taxes for building schools, hospitals and roads. The opportunity is limited because the number of children under five peaked in 2007 and the number under 15 in 2011, and after 2050 India's population will begin to age. To benefit, India must invest in good education, skilling and healthcare, create jobs and provide childcare and supportive systems so that women can join the workforce.

Example 5: Case: Kerala and Bihar · 4 marks · Case-basedHOTS / competency

Read the case and answer.

NCERT notes that states like Kerala and Tamil Nadu are already experiencing significant population ageing as compared to Bihar and Uttar Pradesh. In NCERT's table, Bihar has a fertility rate of 3.0 and women's literacy of 55 per cent, while Karnataka has 1.7 and 73.4 per cent, and Delhi 1.6 and 83.7 per cent.

(i) Which of the three states listed has the lowest fertility rate? (1)
(ii) What relationship between literacy and fertility do you see? (1)
(iii) Why might a state with a high share of elderly people need different policies from Bihar? (2)

Try it first, then show the solutionSolution

(i) Delhi, 1.6 (1 mark).
(ii) As women's literacy rises, fertility falls (1 mark).
(iii) A state with many elderly needs healthcare, care facilities and pensions, while a state with many young people needs schools and jobs (2 marks).

Answer: (i) Delhi, with a fertility rate of 1.6. (ii) States with higher women's literacy have lower fertility rates. (iii) A state with a higher share of the elderly needs more healthcare, care services and pension support, whereas a state with a large young population needs schools, skilling and jobs.

Where students lose marks in Population Composition, Pyramids and the Demographic Dividend

The slips examiners see most often, and what to write instead.

Mistake: Computing sex ratio the wrong way round
Males first by habit.
Wrong working
Sex ratio = males / females x 1,000.
Right working
Sex ratio = females / males x 1,000.
Do this: Say 'females per 1,000 males'.
Usually costs: 1-2 marks.
Mistake: Interpreting a narrow base as growth
Misreading pyramids.
Wrong working
A narrow base means a fast-growing population.
Right working
A narrow base means fewer children: slowing growth.
Do this: Base = births.
Usually costs: 1 mark.
Mistake: Calling the dividend permanent
Ignoring the 2050 limit.
Wrong working
India will have a demographic dividend forever.
Right working
It is a limited window; ageing begins after 2050.
Do this: Add the dates.
Usually costs: 1 mark.

Exam tips

Mention that working-age bands differ in NCERT's text (15-64 in the glossary, 15-59 for India's figure); quote the band as the text does.
Always show the unit 'per 1,000' for sex ratio and check by multiplying back.
Name the shape of a pyramid and what it says about births, workforce and the elderly.
In long answers, pair a challenge with a policy response.

Practice questions on Population Composition, Pyramids and the Demographic Dividend

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
India's sex ratio in Census 2011 was:
(a) 933
(b) 943
(c) 963
(d) 1,000
Hint
It improved from 2001.
Answer
(b) 943
Q2 · 2 marks · Very short answerBoard level
What does a wide base in a population pyramid show? (2 marks)
Hint
Many births.
Answer
A wide base shows that many children are being born, so the country has a young and growing population, as in India in the 1950s or in Nigeria.
Q3 · 3 marks · Short answerHarder board level
A district has 7,50,000 males and 7,05,000 females. Find its sex ratio and say what it suggests. (3 marks)
Hint
Females / males x 1,000.
Answer
Sex ratio = 7,05,000 / 7,50,000 x 1,000 = 940 females per 1,000 males. It is slightly below India's 943 in 2011, suggesting fewer females than males in the district. Check: 7,50,000 x 0.94 = 7,05,000.
Q4 · 1 mark · Assertion-reasonHarder board level
Assertion (A): A country with a median age of 50 is likely to face ageing challenges.
Reason (R): A high median age means a larger share of older people relative to the young.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Hint
Japan's median age in NCERT's table is 50.
Answer
(a) Both A and R are true, and R is the correct explanation of A.
Q5 · 5 marks · Long answerHOTS / competency
Compare India and Japan using median age, pyramid shape and policy challenge, and suggest two measures each country might take. (5 marks)
Hint
Median ages 28 and 50; India's dividend; Japan's ageing.
Answer
India's median age is 28 and Japan's is 50, so India is young and Japan is old. India's pyramid is bell-shaped with a wide working-age middle, while Japan's has a wide top and narrow base. India's challenge is to use its demographic dividend through education, skilling, health and jobs before ageing sets in after 2050; it can also provide childcare and flexible work for women. Japan's challenge is to support an ageing society while maintaining productivity; it has raised the retirement age and uses technology and automation, community centres and robots and AI assistants to care for older adults. Thus the same demographic forces create different needs in each country.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.What is a youth bulge?Show answer
A large young population (16 to 30 years), common in Stage 2 of demographic transition.
2.What was India's sex ratio in 2001?Show answer
933 females per 1,000 males.
3.Which country has a median age of 50 in NCERT's table?Show answer
Japan.
4.When did the number of children under five in India peak?Show answer
2007.
5.What is the 'double burden' for women?Show answer
Managing both job responsibilities and household duties.

Population Composition, Pyramids and the Demographic Dividend: frequently asked questions

What is a population pyramid?

A graph showing a population by age groups and gender, whose shape shows whether the population is young, stable or ageing.

What is India's demographic dividend?

The growth potential from its large young working-age population, nearly 65 per cent of the total, which depends on education, skilling and jobs.

Why is an ageing population a challenge?

More elderly people need healthcare and care while fewer young workers and taxpayers support them, which can slow the economy and strain pensions.