The difference between C.I. and S.I. on an amount of $10,000 for 2 years is $49. What is the rate of interest per annum?  Options:
A) 5%  B) 6%  C) 7%  D) 8%  E) 9%
$49 is the interest on the first year of interest.   Let x be the interest rate.   The interest after the first year is 10000*x.   The interest on the first year's interest is 10000*x*x   10000*x^2 = 49   x = 0.07   The answer is 7%.
<result>C</result>
The difference between C.I. and S.I. on an amount of $10,000 for 2 years is $49. What is the rate of interest per annum?