A certain sum invested at 4% per annum compound interest compounded half yearly, amounts to Rs.15606 at the end of one year. The sum is:

15000

Given rate = 4%

Time = 1 year

( The interest is compounded half yearly then, )

Effective rate will be = 2 + 2 + \(\frac{2 × 2}{100}\) = 4.04%

Amount = Principle + interest = 100% + 4.04% = 104.04%

104.04% = 15606

100% = 15000 (Sum)