Answer:

Step-by-step explanation:
Given information:
Maximum revenue = 42000
Minimum revenue = $25000
Time period = 12 months
We need to write a function that models the boutique's revenue during the year, where corresponds to the month.
.... (1)
where, A is amplitude,
is period, C is phase shift and D is midline.




Substitute the value of A, B and D in equation (1).
..... (2)
In April, revenue of the store is $42000. So, the graph passes through the point (4,42000).



Divide both sides by 8500.


On comparing both sides we get




Substitute the value of C in equation (2).
Therefore, the required function is
.