Step by step
The question
Question: find the population density when the population is 8000 people and the area is 40 km².
Population 8000 people, area 40 km². Find the population density.
1 Write the rule
The rule: population density is the population divided by the area.
population density = populationarea
Population density tells us how many people live on 1 km².
So its unit is people per km².
population density = the people on 1 km²
unit: people ÷ km² → people/km²
2 Put the numbers in
The population is 8000.
The area is 40.
d = 800040
3 Work it out
Careful!
The population goes on the top.
The unit, people/km², shows it: people on the top.
Careful: not 408000 ✗
8000 divided by 40 is 200.
population density = 200 people/km²
Both end in a zero: we cross it out first.
800 divided by 4 is 200.
8000 ÷ 40 = 800 ÷ 4 = 200
So the population density is 200 people/km².
4 Check
Let's check.
200 in each km², for 40 km²: 200 times 40 is 8000.
That is the population.
So the answer is right!
200 people in each km²: 200 × 40 = 8000 people
Let's look back.
First: write the rule.
Then: put the numbers in.
Then: work it out.
Last: check.
Answer
8000 ÷ 40 = 800 ÷ 4 = 200