An amount at compound interest sums to Rs.17640/- in 2 years and to Rs.18522/- in 3 years at the same rate of interest. Find the rate percentage? Choose the correct choice.
A) 5%  B) 6%  C) 7%  D) 8%  E) 9%
The difference of two successive amounts must be the simple interest in 1 year on   the lower amount of money.   S.I = 18522/- - 17640/- = Rs. 882/-   Rate of interest = (882/17640) × (100/1) =&gt; 8820/1764= 
<gadget id="calculator">8820/1764</gadget>
<output>5</output>
5%   Principal= 5%mount/(1 + R/100)n   = 17640/(1 + 5/100)2   = 17640/(21/20 × 21/20)   = 17640/(1.05 × 1.05)   = 17640/1.1025= 
<gadget id="calculator">17640/1.1025</gadget>
<output>16_000</output>
16000   Thus the principal is Rs.16000/- and the rate of interest is 5%   5%
<result>A</result>
An amount at compound interest sums to Rs.17640/- in 2 years and to Rs.18522/- in 3 years at the same rate of interest. Find the rate percentage?