Question

The rate of increase in population is 25% per annum. What will be the population after 2 years if the initial population is 20,000?

• A. 31250
• B. 31,550
• C. 32,250
• D. 32,550

Answer 1

The correct option is A 31250

The rate of increase in population is the increase in population compared to the previous year.
We use the concept of compound interest to find the population after two years.

A = P × ${[1+\frac{R}{100}]}^n$

where, A = population after two years

P = initial population = 20,000

Time (n) = 2 years

Rate (R) = 25%

$\therefore$ A = 20,000 × ${[1+\frac{25}{100}]}^2$ = 31,250

After 2 years the population will be 31,250.