Answer:

Step-by-step explanation:
Use a sinusoidal function of the form

A is the amplitude, obtain the difference between the highest and the lowest value, and then divide by two:

D is the vertical shift, is equal to the lowest value plus the amplitude:

B is the frequency, being 12 months for each cycle (period T=12) and the relation between the period and the frequency is:


Finally, for C the phase shift, the highest value in a sine function the highest point is in the first quartes of the period if the period is 12, then this maximum is in x=3. In the data the highest is in x=7, so the phase shift is to the right and equal in value to 4 (C=4).
So:


For the form 
multiply C by B to find E (
):
