Population and urbanisation, Year 9

Mumbai

HintIt is India's biggest port, on the west coast, and the home of Bollywood.

The whyEstimates suggest that between 600,000 and a million people live there, in just over two square kilometres. It is also a busy workplace, with thousands of small workshops and a large informal recycling trade.

They could be evicted and lose everything they have built

HintImagine being told to leave next week with no compensation.

The whyWithout deeds, a home can be cleared with little warning, so investing in brick walls or a proper roof is a gamble. When residents are given secure ownership, they usually start improving their homes themselves.

sewage

HintIt is the waste that drains and toilets are meant to carry away.

The whyShared taps and open drains mean clean and dirty water mix, especially in the rainy season. Clean water and sanitation usually improve health more than any other single change.

A self-help scheme

HintIts name is the opposite of waiting for someone else to do the work.

The whyThis is a bottom-up improvement: decisions and labour come from the community, not from a distant ministry. It works because it is cheap, it builds on skills people already have, and families look after homes they own.

GDP per person is an average, so it hides how unevenly income is shared

HintPicture one billionaire and nine neighbours with nothing: work out what each 'has' on paper.

The whyGDP per person divides a country's total output by its population. If most of the income goes to a few, the figure can look healthy while many people struggle — and it says nothing about health or schooling at all.

500

HintShare the total output equally among everyone who lives there.

The whyDividing 40 billion by 80 million gives the answer. Dividing by population is what lets a small country be compared fairly with a giant one: total GDP mostly tells you how many people a country has.

Country B

HintLook past the money column to the column about health.

The whyA is richer on paper, but B's people live 14 years longer, which suggests its income reaches more people as clean water, food and healthcare. Using two indicators instead of one changes the verdict.

Life expectancy

HintIt is one of the three ingredients of the Human Development Index, alongside schooling and income.

The whyBecause it reflects food, clean water, healthcare and safety all at once, it is one of the most telling single measures of development. It is the figure the United Nations uses for the health part of its index.

Africa south of the Sahara

HintIt is the continent crossed by the Equator, the Nile and the Congo.

The whyOf the 25 economies in the World Bank's low-income group, 21 are in sub-Saharan Africa (2026 classification). The region is far from uniform, though: it also includes many middle-income countries, such as Kenya and Ghana.

Raw materials and profits were taken abroad, with little invested locally

HintAsk where the wealth from the mines and plantations ended up.

The whyColonies were organised to supply crops and minerals to the ruling country. Railways ran from mine to port instead of linking towns, and few factories, schools or universities were built, so new nations started with economies shaped for someone else's benefit.

landlocked

HintThe word describes being shut in by other countries on every side.

The whyThe UN lists 32 landlocked developing countries, among them Bolivia, Nepal and Uganda, and says they pay more than double their coastal neighbours' transport costs. It is one geographical cause of the development gap.

Many countries south of the line have since become much wealthier

HintThink of China, Singapore, Malaysia and the Gulf states today.

The whyThe Brandt Line reflected the world of its day. Incomes have since risen fast across much of Asia and Latin America, so the World Bank now uses four income groups: the pattern is a spectrum, not two blocks.

Development aid

HintIt is the slow, patient partner of emergency relief.

The whyEmergency aid keeps people alive this week; this kind tries to make sure they are better off in ten years. A well, a trained nurse or a vaccination programme goes on working long after the money was spent.

Processing adds value, so finished goods sell for much more

HintCompare the price of a sack of beans with the price of the bars made from it.

The whyCôte d'Ivoire and Ghana grow about half the world's cocoa (2024–25), yet most of the money is made where it is roasted, branded and sold. Raw material prices also swing sharply between one year and the next, making incomes hard to plan.

Fairtrade

HintIts name joins a word for 'just' to a word for buying and selling.

The whyThe minimum price is a safety net for when world prices crash, and an extra premium goes to community projects chosen by the farmers. It is paid to farmers' co-operatives that meet the scheme's standards.

It meets short-term needs but does not build lasting income

HintAsk what is left once the tents, food parcels and rescue teams have gone.

The whyFood, shelter and medicine are essential in a crisis, but they are used up. Closing the gap needs things that keep producing: schools, roads, jobs and fair access to markets.