A good answer might be:

As many as required by the program. A class is a pattern that can be followed an unlimited number of times.

The picture at left shows a parent class and a child class, and some objects that have been constructed from each. These objects are shown as rectangles (to convey the idea that they are more real than the classes, which are only designs.)

In the picture, "Joe's car," "Mary's Ford," and "Bob's Ford" represent actual objects. The cloudy classes represent designs that were used to construct the objects.

QUESTION 4:

• How many types of automobile are there in the diagram?
• How many automobiles are there in the diagram?