5
D
emography is the study of population.
Population means the total number of
people that live in an area. For example, the
population of the world is more than 7 billion
people. That’s more than 7000 million! This
number is constantly changing because
people are born and die every minute.
The population of the world is not evenly
distributed. In some areas, such as cities,
there are many people. In other areas, such
as deserts and mountain ranges, there are
few people. The number of people living in
each square kilometre is called the population
density. If there are a lot of people living
in each square kilometre, the population
density is high.
Mexico City has a very high population density − many
people live there.
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