Question

Q. If the difference between the C.I and S.I on Rs 12000 for 3 years is Rs. 132.2, find the rate of interest.

• A. 4%
• B. 7%
• C. 6%
• D. 5%

Answer 1

The correct option is C 6%

From formulas for C.I. and S.I. we can find out that difference between C.I. and S.I. for 3 years $=P{r}^3+3P{r}^2$
Where r = $\frac{R}{100}$
$12000\times r^3+36000\times r^2=132.2$
It is easier to check the options than trying to solve the cubic equation By checking option c
$12000\times {0.06}^3+36000\times {0.06}^2=132.192=132.2$