the water level in a bathtub is directly proportional to the time that the water has been running. If the water level is 4 inches after 5 minutes, what is the water level after 11 minutes?
Since the level is proportional to the time, when the time increases from 5 to 11 (by a factor of 11/5), we expect the water level to increase by a factor of 11/5 to ...
