In how many years will a sum of money doubles itself at 5% per annum on simple interest?  Pick one:  A) 29%  B) 20%  C) 07%  D) 50%  E) 23%
P = (P*5*R)/100   R = 20%   Answer:20%
<result>B</result>
In how many years will a sum of money doubles itself at 5% per annum on simple interest?