The fuel tank of a certain airplane can hold up to gallons of fuel. Let be the total weight of the airplane (in pounds). Let be the total amount of fuel in its tank (in gallons). Suppose that gives as a function of .

A reasonable function is W = 7F + 5000

Where W is the weight of the plane and F is the number of gallons of fuel.

The domain is the set of possible values for F. That is from 0 (empty tank) to 400 (full tank).

So the domain is F = [0,400], or what is equivalente 0 ≤ F ≤ 400.

The range is the set of values of W.

The minimum value of W is when F = 0 => W = 7(0) + 5000 = 5,000.

The maximum value of W is when F = 400 => W = 7(400) + 5000 = 7,800

So the range is W = [5,000 ; 7,800], pr 5000 ≤ W ≤ 7,800.