The amount she pays is modeled by an exponential function given below
Where a is the initial fine ($125), b is the growth factor, and x is the number of months.
The growth factor is the ratio of any two consecutive terms
So, the exponential model becomes
Part b:
Using your function, predict how much Katie will pay if she waits until month 12 to pay her fine.
Let us substitute x = 12 into the above function
Therefore, she will have to pay $392.30 if she waits until month 12 to pay her fine.