The compound interest earned on a sum for the second and the third years are $1400 and $1540 respectively. What is the rate of interest?
Choose the correct choice from the following answers:  A) 2%  B) 4%  C) 6%  D) 8%  E) 10%
1540 - 1400= 
<gadget id="calculator">1540 - 1400</gadget>
<output>140</output>
140 is the rate of interest on $1400 for one year.   The rate of interest= (100 * 140) / (1400)= 
<gadget id="calculator">(100 * 140) / (1400)</gadget>
<output>10</output>
10%   The answer is 10%.
<result>E</result>
The compound interest earned on a sum for the second and the third years are $1400 and $1540 respectively. What is the rate of interest?