Question

What is the least number of complete years in which a sum of money at $20\%$ compound interest will be more than doubled?

• A. $7$
• B. $6$
• C. $5$
• D. $4$

Answer 1

Answer: (D)

$4$

Let Principal amount $=RsP$

formula of compound interest,

Amount $=P{(1+\frac{r}{m})}^{mt}$

Acc. to question,

$2P=P{(1+\frac{20}{100})}^t$

$\Rightarrow 2=(1.2{)}^t$

$\Rightarrow t=4$