Answer
$V(t)=2250+250 sin(\frac{π t}{2})$
Work Step by Step
The average volume is 2250 mL.
The amplitude of the graph is 250 mL.
The period is 4 seconds.
We can use these values to write a function that models the depth:
$V(t)=2250+250 sin(\frac{2π }{4}t)$
$V(t)=2250+250 sin(\frac{π t}{2})$