Question

In how many years will a sum of money double itself at 8% per annum interest?

• A. 10 years
• B. 12.5 years
• C. 13 years
• D. 11.5 years

Answer 1

The correct option is B 12.5 years

Let Principal $\left(P\right)=Rs.a$, Time $\left(T\right)=T$ years, Rate $\left(R\right)=8\%$ and Amount $\left(A\right)=Rs.2a$

Using formula, $A=P+SI$, we get, $SI=Rs.a$

Therefore,

$SI=\frac{P\times R\times T}{100}$

$\Rightarrow a\times 100=a\times T\times 8$

$\Rightarrow T=\frac{100}{8}=12.5$ years