You can put this solution on YOUR website! Assuming 8% is the annual interest rate.
t = number of months.
(0.08/12) * 100 = Monthly % rate.
5000 * (1+(1/150))^t = 10000
(1+(1/150))^t = 10000/5000
(1+(1/150))^t = 2
log (1+(1/150))^t = log 2
t * log 1+(1/150) = log 2
t = log 2/log 1+(1/150)
t = 104.3 (1 dp)
So it will take roughly 104 and 1/3 months to double or about 8.7 years.
