The current birth rate in a region is 32 per thousand people and the corresponding death rate is 11 per thousand people. What is the net growth rate of the population expressed as a percentage increase per year?

Introduction / Context:
This question focuses on interpreting crude birth and death rates, commonly given as numbers per thousand population. The net population growth rate is determined by the difference between birth and death rates. Converting that net value into a percentage of the total population is a standard task in population studies and basic demographic mathematics.

Given Data / Assumptions:

Birth rate = 32 per 1000 population.

Death rate = 11 per 1000 population.

Net growth rate is taken as births minus deaths per 1000 people.

We need the net growth rate as a percentage.

Concept / Approach:
The net increase per 1000 people is given by:
net increase per 1000 = birth rate − death rate.
Once we find this net figure, we convert it to a percentage by interpreting it as so many per 1000, and then expressing that as an equivalent per 100 (percent). Since percent means per hundred, dividing the per thousand figure by 10 gives the net growth in percent.

Step-by-Step Solution:
Step 1: Net increase per 1000 people = birth rate − death rate.Net increase = 32 − 11 = 21 per 1000.Step 2: Convert 21 per 1000 to a percentage (per 100).21 per 1000 = 21 / 1000.Multiply by 100 to get percentage: (21 / 1000) * 100 = 2.1%.Step 3: Therefore the net growth rate is 2.1% per year.

Verification / Alternative check:
Think of a population of 1000 people. In one year, there are 32 births and 11 deaths, so the population increases by 21, ending at 1021. The growth factor is 1021 / 1000 = 1.021. As a percentage, the growth is (1.021 − 1) * 100 = 2.1%. This is consistent with the earlier direct calculation.

Why Other Options Are Wrong:
1.2%, 1.3%, and 2.5% are not equal to 21 / 1000 expressed as a percentage.
3.1% would correspond to a net increase of 31 per 1000, which does not match the given rates.

Common Pitfalls:
Some students mistakenly add birth and death rates instead of subtracting them, or attempt to average them. Others confuse per thousand with percentage and forget to divide by 10 to move from per 1000 to per 100. Always remember that net growth is births minus deaths, and that converting from per 1000 to percent requires multiplying by 100 and dividing by 1000.

Final Answer:
The net population growth rate is 2.1% per year.