# If a sum of money at a certain rate of simple interest per year doubles in 5 years :

If a sum of money at a certain rate of simple interest per year doubles in 5 years and at a different rate of simple interest per year becomes three times in 12 years, then the different in the two rates of simple interest per year is

(a) 2%

(b) 3%

(c) 10/3%

(d) 13/3%