Let the sum be Rs. 100. Then,
S.I. for first 6 months = Rs.100 x 10 x 1 / 100 x 2= Rs. 5
S.I. for last 6 months = Rs.105 x 10 x 1 / 100 x 2= Rs. 5.25
So, amount at the end of 1 year = Rs. (100 + 5 + 5.25) = Rs. 110.25
Effective rate = (110.25 - 100) = 10.25%