Exponential growth functions are the functions that normally take the form
y=ab^x
where:
a=initial value
b=growth rate
x=time
An example of situation that takes this form is the population growth of a particular group say and organism.
X is 90 degrees. If AB is the diameter, then it passes through the centre. X is 90 degrees because the angle in a semicircle is always a right angle.
You are told that sprinklers run for the same amount of time. lets refer to this time as T.
you are told that 4 sprinkles run one at a time for 50 minutes total. that means that T should be 50/4 = 12.5 minutes = 12 minutes and 30 seconds