Web-based exercise. The Web abounds in applets that simulate various random phenomena. One amusing probability problem is named Buffon’s needle. Draw lines 1 inch apart on a piece of paper, then drop a 1-inch-long needle on the paper. What is the probability that the needle crosses a line? You can find both a solution by mathematics and a simulation at George Reese’s site, www.mste.uiuc.edu/reese/buffon/buffon.html.

Visit the site and try the simulation 100 times. What do you get as your estimate of the probability?

Personal sites sometimes vanish; a search on “Buffon’s needle” will turn up alternative sites. The probability turns out to be 2/π, where any circle’s circumference is π times its diameter. So the simulation is also a way to calculate π, one of the most famous numbers in mathematics.