The answer to this question is 98000
To write the function to show the weekly growth rate of population , we first find the weekly growth rate by dividing yearly growth rate by 52 ( as there are 52 weeks in an year)
Given function is ,

or

To convert in weekly growth rate , divide 0.016 by 52
So formula for weekly growth rate of population is

or

And the weekly growth rate = 
Ok what am I supposed to answer?
We are not given tables, so will just use the amortization formula.

where
P=amount to be deposited today, to be found
A=amount withdrawn each year=18000
i=Annual interest=9%
n=number of years = 20
Substituting values,

=164313.82 to the nearest cent