A mathematical puzzle whose essential nature involves randomness. Use with [mathematics]
A probability puzzle is a puzzle, usually mathematical, that involves uncertain outcomes.
Probability puzzles often involve coin-tossing, dice, or cards, although other mechanisms may act as sources of uncertain outcomes.
For example: Left coin, right coin, last coin?
Another example of a probability puzzle is the Monty Hall problem: the game show problem with three doors, one car, and two goats.
General probability questions are off-topic but can be asked on our sister site Mathematics Stack Exchange with the probability tag (some questions can be found here).