Section 4.1 Reference Topics
You can explore Example 9 by playing with this interactive site called The Monty Hall
Dilemma:
http://www.cut-the-knot.com/hall.html
There is an introduction to probability at this excellent site:
http://mathforum.org/dr.math/faq/faq.prob.intro.html
Here is an interactive coin-flipping site:
http://shazam.econ.ubc.ca/flip/
Here is an interactive site for rolling one or two dice.
http://www.eserc.stonybrook.edu/ProjectJava/lisa1998/prob/