In how many years will a sum of money doubles itself at 5% per annum on simple interest?  Pick.
A) 80%	B) 20%	C) 28%	D) 90%	E) 30%
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?