Simple interest on a certain sum at 7% per annum for 4 years is Rs. 2415. What will be the compound interest on the same principal at 4% per annum in two years?

We know that,

$S.I. = \frac{\mathrm{PTR}}{100}\Rightarrow P = \frac{S.I x 100}{T x R}\mathrm{And} \mathrm{also},C.I = P1 + \frac{R}{100}n- 1$

From given data, P = Rs. 8625

Now, C.I  =  $86251+\frac{4}{100}2-1= 8625\frac{26}{25}2-1= 8625\frac{676}{625}-1= 8625 x \frac{51}{625}C.I = \mathrm{Rs}. 703.80$