Question

A certain sum becomes 8 times in 3 years at compound interest, compounded annually. Find the rate of interest.

• A. $70\%$
• B. $88\%$
• C. $100\%$
• D. $122\%$

Answer 1

Answer: (C)

$A=P(1+\frac{r}{100}{)}^t$
$8P=P(1+\frac{r}{100}{)}^3$
$\sqrt[3]{8}=1+\frac{r}{100}$
$2=1+\frac{r}{100}$
$1\times 100=r$
$r=100\%pa$