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 answers.
A) 18% p.a.  B) 22% p.a.  C) 20% p.a.  D) 24% p.a.  E) None of these.
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?