A 50-gallon (gal) bathtub contains 20 gal of water and is filling at a rate of 2.4 gal / min. You check the tub every minute on the minute.
a. Suppose that the drain is closed. When will you discover that the water is flowing over the top?
b. Now suppose that the bathtub contains 20 gal of water and is filling at a rate of 2.4 gal / min, but the drain is open and water drains at a rate of 3.1 gal / min. When will you discover that the tub is empty?
c. Write a recursive formula that you can use to find the water level at any minute due to both the rate of filling and the rate of draining.