A sum of money invested at C.I. amounts to Rs. 800 in 3 years to Rs. 880 in 4 years. The rate of interest per annum is?
Choose the correct option
A) 2 1/2 %
B) 4%
C) 10%
D) 6 2/3 %
E) 6%
S.I. on Rs. 800 for 1 year = (880 - 800) = Rs. 80 Rate = (100 * 80)/(800 * 1)= 
<gadget id="calculator">(100 * 80)/(800 * 1)</gadget>
<output>10</output>
10%   ANSWER:10%
<result>C</result>
A sum of money invested at C.I. amounts to Rs. 800 in 3 years to Rs. 880 in 4 years. The rate of interest per annum is?