Question

A lake has a small population of a rare endangered fish. The lake currently has a population of 11 fish. The number of fish is increasing at a rate of 5% per year. When will the population double? How long will it take the population to be 44 fish? If necessary, round your answer to the nearest whole number.
The population will double in approximately
years.
?

The population will be 44 in approximately years.
?

Answer 1

5% of 11 is 0.55. What number times 0.55 = 11? Well if we divide 11 by 0.55, we see that the answer is 20. So, the population will double in 20 years. If the population is 22 in 20, it stands to reason that it will take another 20 years to double from 22 to 44. So, the population will reach 44 in 40 years.

Hope this helps.