A sum is invested at compounded interest payable annually. The interest in the first two successive years was Rs. 400 and Rs. 420. The sum is  Choices:
A) Rs. 8000
B) Rs. 8200
C) Rs.7500
D) Rs. 8500
E) Rs. 8600
Explanation:   his means that, simple Interest on Rs.400 for 1 year = 420 - 400= 
<gadget id="calculator">420 - 400</gadget>
<output>20</output>
20   Rate= (100 ×SI)/PT = (100 × 20)/(400×1) = 5%   Rs.400 is the interest on the sum for 1st year   Hence, sum = (100 × SI)/RT = (100 × 400)/(5 × 1) = Rs. 8000   Rs. 8000nswer: Option Rs. 8000
<result>A</result>
A sum is invested at compounded interest payable annually. The interest in the first two successive years was Rs. 400 and Rs. 420. The sum is