
In Las Vegas, Phil has $20 but needs $40 for a show at the Sphere, but he is too embarrassed to ask his wife Claire for more money. He decides to invest in roulette and is considering two strategies: bet the $20 on "evens" all at once and quit if he wins or loses, or bet on "evens" one dollar at a time until he has won or lost $20.
Which is the better strategy?