Question

At a certain rate of simple interest, a certain sum doubles itself in 10 years. It will triple itself in

• A. 12 years
• B. 15 years
• C. 20 years
• D. 30 years

Answer 1

The correct option is C 20 years

Since sum double itself in 10 years, so sum = S.I. for 10 years.

Let sum $=x$. Then, S.I. $=x$ and Time $=10$ years.
$\therefore Rate=\left(\frac{100\times x}{x\times 10}\right)$% $=10$%
Now, sum $=x$, S.I. $=2x$, Rate $=10$%
$\therefore$ Time $=\left(\frac{100\times 2x}{x\times 10}\right)years=20$ years.