Question

The population of city increases at the rate of the annually. Its present population is 90.51 lakh. The population 3 years ago was nearly.

• A. 72 lakh
• B. 68 lakh
• C. 80 lakh
• D. None of these

Answer 1

The correct option is B 68 lakh

We have, P = 90.51, r = 10 and n = 3.
$\therefore$ The population 3 years ago
$=\frac{P}{{(1+\frac{r}{100})}^n}=\frac{90.51}{{(1+\frac{10}{100})}^3}$

$=\frac{9051}{100}\times \frac{100}{110}\times \frac{100}{110}\times \frac{100}{110}=68lacs.$