Question:
The population of a town increases at the rate of 50 per thousand. Its population after 2 years will be 22050. Find its present population.
Solution:
Population after two years $=\mathrm{P}\left(1+\frac{\mathrm{R}}{100}\right)^{\mathrm{n}}$
$22,050=\mathrm{P}\left(1+\frac{50}{1000}\right)^{2}$
$22,050=\mathrm{P}(1.05)^{2}$
$\mathrm{P}=\frac{22,050}{1.1025}$
$=20,000$
Thus, the population two years ago was 20,000 .