A graph such as this shows the increase that occurs in any quantity that is growing at a fixed percentage of its current size. A savings account earning compound interest grows this way, and so does the human population.
Populations grow much the same way that money does in a savings account.
To calculate the doubling time for population, you would use the same formula. This rate may not seem ominous, but if we use the same mathematical formula as we did for calculating the doubling time of money, we can determine the doubling time for the world s population.