1. The number of miles a car can travel on a gallon of gasoline is related to its fuel
efficiency. Fuel efficiency depends on many factors including the speed of the car.
Driving at very slow or very fast speeds uses more gas than driving at a moderate
speed, which means fuel efficiency can often be modeled by a quadratic function.
For a certain model of car the fuel efficiency is maximized at 32 miles per gallon
with a speed of 55 mph. At 65 mph the car can get 31 miles per gallon.