20.28 Casino winnings. What is a secret, at least to naive gamblers, is that in the real world, a casino does much better than expected values suggest. In fact, casinos keep a bit over 20% of the money gamblers spend on roulette chips. That’s because players who win keep on playing. Think of a player who gets back exactly 95% of each dollar bet. After one bet, he has 95 cents.
(a) After two bets, how much does he have of his original dollar bet?
(b) After three bets, how much does he have of his original dollar bet?
Notice that the longer he keeps recycling his original dollar, the more of it the casino keeps. Real gamblers don’t get a fixed percentage back on each bet, but even the luckiest will lose his stake if he plays long enough. The casino keeps 5.3 cents of every dollar bet but 20 cents of every dollar that walks in the door.