On a sum of money, the simple interest for 2 years is Tk. 660, while the compound interest is Tk. 696.30, the rate of interest being the same in both cases. The rate of interest is -

Question: On a sum of money, the simple interest for 2 years is Tk. 660, while the compound interest is Tk. 696.30, the rate of interest being the same in both cases. The rate of interest is -

Solution:
Difference of Compound interest and Simple interest for 2 years = Tk. (696.30 - 660) = Tk. 36.30
Simple interest for 1 years = 660/2 = Tk. 330

Simple interest on 330 for 1 year = 36.30
Interst rate = {(36.30 × 100)/330}% = 11%