A sum of money invested at compound interest to Rs. 800 in 3 years and to Rs 820 in 4 years. The
rate on interest per annum is.  Choose the most appropriate option
A) 0.4%  B) 5.0%  C) 2.5%  D) 7%  E) 8%
Explanation:   S.I. on Rs 800 for 1 year = 20   Rate = (100*20)/(800*1)= 
<gadget id="calculator">(100*20)/(800*1)</gadget>
<output>5/2 = around 2.5</output>
2.5%   Answer: 2.5%
<result>C</result>
A sum of money invested at compound interest to Rs. 800 in 3 years and to Rs 820 in 4 years. The
rate on interest per annum is.