Question

If $Rs.600$ are invested at $5\%$ simple interest per annum, in how much time it will double itself?

Answer 1

Give: Initial investment $=Rs.600$

If it doubles itself it becomes $2\times 600=Rs.1200$

So simple interest earned $=Rs.(1200-600)=Rs.600$

So, Principal, $P=Rs.600$

Interest, $S.I=Rs.600$

Rate, $R=5\%$

Time, $T=?$ years

Simple interest, $S.I=\frac{P\times R\times T}{100}$

$\Rightarrow 600=\frac{600\times 5\times T}{100}$

$\Rightarrow 600=30T$

$\Rightarrow T=\frac{600}{30}=20$ years

Hence, $Rs.600$ will double itself in $20$ years.