Question

The population of a city is 7.26 lakh today. If the population has been increasing at the rate of 10% per year, then two years ago, the population would have been 

(a) 6 lakh 

(b) 5.5 lakh 

(c) 5 lakh 

(d) 4.5 lakh

Answer 1

(a) 6 lakh

Let the population 2 years ago be x. Then,

7.26 = x\(\big(1+\frac{10}{100}\big)^2\) \(\Rightarrow\) 7.26 = x x \(\frac{11}{10}\) x \(\frac{11}{10}\)

\(\Rightarrow\)x = \(\frac{7.26\times100}{121}\) = 6 lakh