If 90 ants are found in a field with a total area of 100 m. what is the population density of the ants?

Analyze the question: We're asked for the population density of ants: the number of organisms per unit area.

Concept:

Population density = Number of individuals ÷ Area

Solution:

• Number of ants = 90
• Area = 100 m² (the question writes "100 m", which is a typo for square metres, since area is measured in m²)

Population density = 90 ÷ 100 = 0.90 ants per m²

Answer: Option B (0.90)

Tip: In population density questions, always divide the number of organisms by the area (or volume). If the numbers are 90 and 100, you are dividing a smaller number by a larger one, so the answer must be less than 1. That alone rules out C and D. Also remember to include the unit (per m²) in practical or theory questions.