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 choices:
A) 27%	B) 28%	C) 20%	D) 16%	E) 25%
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%
<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?