Study guides & original practice
Population density practice
Arithmetic population density divides population by land area. It gives an average concentration, not a map of where every resident actually lives.
By ExamCat · Original study lesson · Published September 24, 2026
Understand the method
Keep the same area units when comparing places. A national average can combine crowded cities with sparsely populated land. Physiological density instead uses arable land as its denominator, so it answers a different question.
Worked example, step by step
An invented region has 240,000 residents across 800 km², of which 200 km² is arable.
- Arithmetic density is 240,000/800 = 300 people per km².
- Physiological density is 240,000/200 = 1,200 people per km² of arable land.
- The different results come from different denominators, not different population counts.
- Neither figure establishes that every square kilometer has that number of residents or that every resident works in agriculture.
A mistake to watch for
A high average density does not prove overcrowding at every location. For infrastructure planning, inspect the spatial distribution and the relevant services as well as the summary ratio.
Try it yourself: three questions
Write an answer before opening the explanation. For calculations, keep your units and intermediate steps; for concepts, state the reason for your choice.
1. A town has 15,000 people over 30 km². Find arithmetic density.
Show answer and explanation
500 people per km². Report the area unit with the number.
2. Population doubles while area stays constant. What happens to density?
Show answer and explanation
It doubles under the same definition because the numerator doubles.
3. Why can two places with equal arithmetic density have different food-production pressures?
Show answer and explanation
Their arable land, farming systems, imports and other conditions may differ. Arithmetic density alone does not measure agricultural capacity.
Build your next practice session
Mark the first step where your reasoning differed from the explanation. Turn that step into a question, answer it without looking, then change one condition in the example and explain what would change. A correct guess is a reason to revisit the method.
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Further reading
US Census Bureau: population density provides textbook background. The worked scenario and practice questions on this page were written independently for ExamCat.
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