Question

The present population of a town is 7,98,600. If it increased at the rate of 10% every year, what was its population 3 years ago?

Answer 1

Given, present population = 798600

Rate of growth, r = 10% per annum

Time, n = 3 years

Let the population three years ago be x.

Present population = Population after n years `(1 + r/100)^n`, where r is the rate of growth

∴ `x(1 + 10/100)^3 = 798600`

⇒ `x(11/10)^3 = 798600`

⇒ `x = (798600 xx 10 xx 10 xx 10)/(11 xx 11 xx 11)`

⇒ `x = 600000`

Hence, the population three years ago is 600000.