On a sum of money, the S.I. for 2 years is $600, while the C.I. is $612, the rate of interest being the same in both the cases. The rate of interest is? Choose the correct choice from the following answers.
A) 3 % B) 4 % C) 5 % D) 6 % E) 7 %

Rationale: difference in c . i . and s . i for 2 years = $ 612 - $ 600 = $ 12 s . i for one year = $ 300 s . i . on $ 300 for 1 year = $ 12 rate = ( 100 * 12 ) / ( 300 ) = 4 % the answer is b .
Answer: B