A lent Rs. 4000 to B for 2 years and Rs. 2000 to C for 4 years on simple interest at the same rate of interest and received Rs. 2200 in all from both of them as interest. The rate of interest per annum is :  Pick.
A) 14%  B) 15%  C) 12%  D) 13.75%  E) 14.56%
Explanation:   Let the rate of interest per annum be R%   Simple Interest for Rs.4000 for 2 years at R% + Simple Interest for Rs.2000 for 4 years at R%   = 2200   (4000×R×2)/100 + (2000×R×4)/100 = 2200   80R + 80R = 2200   160R = 2200   16R = 220   4R = 55   R = 55/4= 
<gadget id="calculator">55/4</gadget>
<output>55/4 = around 13.75</output>
13.75%   Answer: Option 13.75%
<result>D</result>
A lent Rs. 4000 to B for 2 years and Rs. 2000 to C for 4 years on simple interest at the same rate of interest and received Rs. 2200 in all from both of them as interest. The rate of interest per annum is :