Question

The population of a small town was 3500 in 2005. The population increases by 4% annually. A. Write an exponential growth function to represent this situation. B. What will the population be in 2025?

Answer 1

Answer: The population in 2025 will be 7669

Step-by-step explanation:

a) When we have an initial quantity A, and we have an increase of the X%, the new quantity is written as:

new quantity = A + A*(X%/100%) = A*(1 + X%/100%)

In this case, our initial quantity is 3500, the town's population in 2005.

And X% = 4%.

We know that each year, the population increases by 4%.

Then if P(1) is the population one year after 2005, this is:

P(1) = 3500*(1 + 4%/100%) = 3500*(1.04)

After another year, the population increases again:

P(2) = (3500*(1.04))*(1 + 4%/100%)) = 3500*(1.04)*(1.04) = 3500*(1.04)^2

Well, we already can see the pattern here, the population N years after 2005 will be:

P(N) = 3500*(1.04)^N

b) Now we want to know the population in 2025.

N represents the number of years after 2005, then we will have:

N = 2025 - 2005 = 20

2025 is 20 years after 2005.

Then the population in 2025 will be:

P(20) = 3500*(1.04)^20 = 7,668.9

And we can not have a 0.9 of a person, so we should round it up to the next whole number, then the population in 2025 will be 7669