Let the sum of money is =P So, the Amount is =3P ⇒A=P(1+r∕n)nt ⇒3P=P(1+r)5 ⇒3=(1+r)5 Time required so that sum become 9 times =t years ⇒9P=P(1+r)t ⇒9=(1+r)t ⇒32=(1+r)t Putting the value in equation 3 from equation 2 ⇒(1+r)2×5=(1+r)t on comparing the RLS and LHS ⇒t=10