Question

An amount of money invested trebled in $6years$. Find the rate of interest earned.

Answer 1

Let $P$ be the sum of money invested initially.

It is given that money invested trebled in $6years$

Time (T) = $6years$

Hence, Amount will be thrice the sun invested.

So, Amount (A) = $3P$

Let $I$be the simple interest .

then , Simple interest (I) =$A-P=3P-P=2P$

$\Rightarrow \frac{P\times R\times T}{100}=2P$

$\Rightarrow \frac{P\times R\times 6}{100}=2P$

$\Rightarrow R=\frac{200}{6}$

$\Rightarrow R=\frac{100}{3}$

$\Rightarrow R=33\frac{1}{3}$

Hence, Rate of interest earned is $33\frac{1}{3}\%perannum$.