Question

The difference between C.I. and S.I. on Rs.7,500 for two years is Rs.12 at the same rate of interest per annum. Find the rate of interest.

Answer 1

$P=7500CI-SI=12$

$T=2yr$

$SI=\frac{PRT}{100}=\frac{7500\times R\times 2}{100}=150R$

$CI=p{(1+\frac{x}{100})}^2-P=7500[(1+{\frac{x}{100}}^2)-1]$

$\Rightarrow 7500(1+\frac{R^2}{100\times 100}+\frac{2R}{100}-1)-150R=12$

$\Rightarrow \frac{3R^2}{4}+150R-150R=12$

$\Rightarrow R^2=\frac{12\times 4}{3}=10$ So $R=4\%$