Skip to content

Stopping a deal to bet the next card is red

Question

A dealer flips cards face up one by one from a shuffled standard deck. At any moment you may say stop, and you win if the next card to be turned is red. With the best possible stopping strategy, what is your highest probability of winning?

Short answer

1/21/2. Given what has been seen, the next card and the bottom card of the deck are equally likely to be red. So any strategy wins with the same probability as betting on the bottom card, which is red with probability 12\tfrac12 regardless of strategy.

Adapted from QuantQuestions.io; question and answer rewritten by SelfMadeQuant.com.

See the hint and the full worked solution in the question bank (free account).

Open the worked solution

Lessons behind this question

Start with a free lesson: Probability Fundamentals is part of a free topic. Create a free account, no card needed, to read it in full with worked solutions.

Read it free