Question

At what percent rate of compound interest will a sum of money becomes $8$ times itself in $3$ years

Answer 1

Let $P$ be the sum.

Amount $\left(A\right)=8P$

$t=3\text{years}$

Rate of interet $\left(R\right)=?$

As we know that,

$A=P{(1+\frac{R}{100})}^3$

$8P=P{(1+\frac{R}{100})}^3$

${\left(8\right)}^{1/3}=1+\frac{R}{100}$

$\Rightarrow \frac{R}{100}=2-1$

$\Rightarrow R=100\%$