A sum of money lent at compound interest for 2 years at 20% per annum would fetch Rs.482 more, if the interest was payable half yearly than if it was payable annually . The sum is

Let sum=Rs.x

C.I. when compounded half yearly =  $x1+\frac{10}{100}4-x=\frac{4641}{10000}$

C.I. when compounded annually = $x\frac{20}{100}2-x=\frac{11}{25}$

  $\frac{4641}{10000}x-\frac{11}{25}x=482$

=> x=20000