A=P(1-r)^t
A is the final amount.
P is the principle or starting value.
Minus because the function is decay or decreasing.
r is the rate as a decimal
t is the years
A=12,500(1-.06)^t
Where t is the years.
For 4 years let t=4
A=12,500(1-.06)^4
A=9,759.362
Assuming you cannot have part of a person, since we are looking at population of a town.
= 9,759
