We will use this formula:
Time = log(ending amount / beginning amount) ÷ log (1 + rate)
For the purpose of this problem we'll say the population grows from 100 to 200.
Time = log (200 / 100) / log (1.05)
Time = log (2) / log (1.05)
Time = .30102999566 / 0.02118929907
Time =
14.207 years