Question

The rate of increase in population is 25% year on year. What will be the population after 2 years if the initial population is 20000?

• A. 20000
• B. 27250
• C. 31250
• D. 35000

Answer 1

The correct option is C 31250

Given, the population increases year on year.

We can find the population after 2 years by using the concept of compound interest.

By using the formula in case of compound interest, the amount for t years can be calculated by

$A=P\times (1+\frac{R}{100}{)}^t$
Similarly, the population after 2 years can be calculated by

$F=I(1+\frac{R}{100}{)}^2$

where F is the population after 2 years,
I is the initial population and R is the rate of increase in population.

On substituting the values in the equation, we get

$F=20000\times (1+\frac{25}{100}{)}^2$
$F=31250$

After 2 years the population will be 31250.