Question

A man saved $\text{Rs}66000$ in $20$ years. In each succeeding year after the first year he saved $\text{Rs}200$ more than what he saved in the previous year. How much did he save in the first year?

Answer 1

Let us assume that the man saved Rs $a$ in the first year.

In each succeeding year, an increment of Rs. $200$ is made.

So it forms an A.P. whose first term is $a$

Common difference $=200$

$n=20$

$S_n=\frac{n}{2}[2a+(n-1\left)d\right]$

We are given, $S_{20}=66000$

$S_{20}=\frac{20}{2}[2a+19d]=66000$

$2a+19\times 200=6600$

$\Rightarrow a=1400$