The exponential growth formula for caclulating exponential growth is y = a(1 + r)^x
In this formula
Y is equal to the future value
a is equal to the present value
r is equal to the rate of growth
x is equal to the number of periods of growth
If we put in what we know we get the following
y = 24,500(1 + .018)^15
This can be simplifyed to give the value of y
(1.018)^15 = 1.306822701
Multiply that by 24,500 to get
y = 32017 people