Suppose you were a contestant on "Let's Make a deal the old television show. The host, Monty Hall, Presents three doors. One hides a luxury car; the others conceal scrawny goats. YOU Must choose The odds Of winning the car are, of course, one Out of three, so without much thought, you pick any door. But then Monty mischievously opens one of the other doors, revealing a goat. Are the odd better if you switch your choice to the other closed door or if YOU stay with your original selection? It seems that it doesn't matter. After all, there are two doors left, so the chance of your being right is one out of two. But actually, if You switch doors, you are twice as likely to win. This bizarre re- sult led to such controversy - even a mis- taken objection by the great mathemati- cian Paul Erdos - that it became a front- page article by John Tierney in The New York Times in 1991. Here's the explanation. Of Course a goat was always behind one of the two uncho- sen doors; Monty's act doesn't reveal any new information. So the initial odds of one out of three remain unchanged. But now for the weird twist. There must be a car behind one of the two closed doors; if the car isn't behind one door, it's behind the other. So if one out of every three times the car is behind the door you've chosen, the other two times it will be behind the other door. This means that the odds of finding the car behind that other door are two out of three. As the audience might have correctly screamed: "Switch!