A population of 5000 people doubles in size every 10 years. Determine the population

after 70 years. What is the time used to solve the problem?

Answer: A quantity grows exponentially when its increase is proportional to what is already there. A common example is compound interest, where $100 invested at 7% per year annual compound interest will double in 10 years. Similarly, if a population grows at 7% per year, it, too, will double in 10 years.