Question

A certain sum is invested on simple interest. If it triples in $10$ years, what is the rate of interest?

• A. $20\%$ p.a.
• B. $15\%$ p.a.
• C. $10\%$ p.a.
• D. $8\%$ p.a.

Answer 1

The correct option is A $20\%$ p.a.

Let the sum=Rs. $x$

Time $=10$ years

It triples in 10 years then amount $=3x$

Simple interest$=3x-x=2x$

$\text{S.I}=\frac{PRT}{100}$

$\therefore R=\frac{\text{S.I}\times 100}{P\times T}$

$\Rightarrow R=\frac{2x\times 100}{x\times 10}=20$ $\%$