The population of a town is 1771561. If it had been increasing at 10% per annum, its population 6 years ago was :

Answer: Option A

Population of 6 years ago :
$$\begin{array}{rl}& =\left[\frac{1771561}{{\left(1+\frac{10}{100}\right)}^6}\right]\\ & =1771561\times {\left(\frac{10}{11}\right)}^6\\ & =\frac{1771561\times 1000000}{1771561}\\ & =1000000\end{array}$$