If the sample interest on a sum of money 20% per annum for 2 years is $400, find the compound interest on the same sum for the same period at the same rate?
Pick.
A) $460 B) $510 C) $440 D) $500 E) $550
Rate = 20%   Time = 2years   S.I. = $400   Principal = 100*400/20*2 = $1000   Amount = 1000(1+20/100)^2 = $1440   C.I. = 1440-1000= 
<gadget id="calculator">1440-1000</gadget>
<output>440</output>
$440   Answer is $440
<result>C</result>
If the sample interest on a sum of money 20% per annum for 2 years is $400, find the compound interest on the same sum for the same period at the same rate?