Higher or Lower on the Next Card
A dealer shuffles a standard -card deck and turns one card face up. Ranks run from ace low () to king (); suits are irrelevant. Looking at that card, you call whether the *next* card off the deck will be higher or lower in rank. A tie -- the next card matching the rank of the face-up card -- counts as a loss.
Playing optimally, what is your probability of winning, and what is the fair price to enter a game that pays on a win and nothing on a loss?
