Let the sum be Rs. 100. Then,
S.I. for first 6 months = (100 x 8 x 1) / (100 x 2) = Rs. 4
S.I. for last 6 months = (104 x 8 x 1) / (100 x 2) = Rs. 4.16
So, amount at the end of 1 year = (100 + 4 + 4.16) = Rs. 108.16
Effective rate = (108.16 - 100) = 8.16%.