The compounding interest formula is :

where A = future amount after t years
P = Initial amount
r = rate of interest
n = number of compounding
From the problem :
P = 5000
r = 7.2% or 0.072
n = 12 (compounded monthly)
Using the formula above :

The function will be :

Additional Information :
The formula was derived from :

where P = principal amoutn
A = future amount
I = Interest
The formula for interest is :

Substitute it to the formula above :

Factor out P :
