A sum of money invested at C.I. amounts to Rs. 800 in 3 years to Rs. 870 in 4 years. The rate of interest per annum is?	Choose the correct answer
A) 2 1/2 % B) 8 3/4% C) 5% D) 6 2/3 % E) 6%
S.I. on Rs. 800 for 1 year = (870 - 800) = Rs. 70 Rate = (100 * 70)/(800 * 1) = 8 3/4%   ANSWER:8 3/4%
<result>B</result>
A sum of money invested at C.I. amounts to Rs. 800 in 3 years to Rs. 870 in 4 years. The rate of interest per annum is?