Question

What will be the ratio of simple interest earned by a certain amount at the same rate of interest for 3 years and for 9 years?

• A. 1:2
• B. 1:3
• C. 1:4
• D. 2:3

Answer 1

The correct option is B

1:3

We know that I = $\frac{PRT}{100}$

where, I is the simple interest, P is the principal, R is the rate of interest per annum and T is the time(number of years).

Simple interest for 3 years will be $I_1$ = $\frac{PR\left(3\right)}{100}$

Simple interest for 9 years will be $I_2$ = $\frac{PR\left(9\right)}{100}$

Ratio of interests will be $\frac{I_1}{I_2}$ = $\frac{\frac{PR\left(3\right)}{100}}{\frac{PR\left(9\right)}{100}}$ = $\frac{3}{9}$ = $\frac{1}{3}$

Hence the required ratio is 1:3