Profit from a favourable stopping game

Each round you win $2 with probability 0.40.4 and lose $1 with probability 0.60.6. You stop the moment you win, or after 33 straight losses - whichever comes first. What is your expected net profit (in dollars, to four decimals)?

Show hints (2)+
  1. First check whether the game is fair - the martingale/optional-stopping shortcut only works if it is.
  2. It has positive edge, so enumerate the four stopping paths and weight their payoffs.

Answer

Reveal answer →

0.392 (± 0.0005)

Create a free account to see the full worked solution and track your progress.

Interview format: Trading Aptitude Tests, Betting Game Rounds

Related questions