Compound interest earned on a sum for the second and the third years are Rs.1200 and Rs.1440 respectively. Find the rate of interest?	Choose the correct choice from the following.
A) 29%p.a
B) 28%p.a
C) 20%p.a
D) 24%p.a
E) 26%p.a
Rs.1440 - 1200   = Rs.240 is the interest on Rs.1200 for one year.   Rate of interest   = (100 * 240) / (100 * 1) = 20%p.a   Answer:20%p.a
<result>C</result>
Compound interest earned on a sum for the second and the third years are Rs.1200 and Rs.1440 respectively. Find the rate of interest?