Population density refers to

Analyze the question: It asks for the definition of population density, a basic concept in the Economics topic of Population.

Explain the concept: Population density tells us how crowded an area is. It measures the number of people living in each unit of land area, usually persons per square kilometre (persons/km²).

Formula:

Population density = Total population ÷ Total land area

Example: Suppose a local government area has 500,000 people living on 250 km² of land.

Population density = 500,000 ÷ 250 = 2,000 persons per km²

Checking each option:

• A. Total population: This is just the headcount. It says nothing about the land area, so it is not density.
• B. Total population divided by total area of land: Correct. This is exactly the formula.
• C. Total area of land divided by total population: This is the inverse (land per person), so it is not population density.
• D. Population ratio of male and female: This is the sex ratio, not density.
• E. Optimum population: This is the population size that gives the highest output per head, which is a different concept.

Answer: The correct option is B.

Exam tip: Think of "density" as "how many per space". The thing being counted (people) goes on top and the space (land area) goes at the bottom. The same pattern holds in Physics, where density = mass ÷ volume.