Question

If the interest charged for 18 months is 0.15 times the money borrowed under simple interest, then the rate of interest per year is _______

• A. $12\%$.
• B. $10\%$.
• C. $15\%$.
• D. $13\%$.

Answer 1

The correct option is B

$10\%$.

Let the money borrowed be Rs. P.
Interest (I) charged $=0.15\times Rs.P=Rs.0.15P$

Using I = $\frac{PRT}{100}$ and substituting P = 0.15P , T = 1.5 years (18 months) we get

0.15P = $\frac{PR\left(1.5\right)}{100}$

Solving we get R = 10%