The graph of the function , where , models the total amount of water , in gallons, in a swimming pool after minutes of filling. What is the best interpretation of the slope of the graph in this context?
\ltimage\gt
The pool initially contains 100 gallons of water.
The pool is filled at a rate of 20 gallons per minute.
It takes 10 minutes to fill 300 gallons.
The pool will contain 500 gallons after 20 minutes.
