Pair-Draw Casino Game: A Sure Bet Against You
You’re in a casino offered a curious card game involving a standard 52-card deck. The rules seem simple—and tempting:
Game Mechanics
- A full 52-card deck is well shuffled.
- Cards are turned over two at a time until the deck is exhausted.
- For each pair:
- If both are red, they go into your pile.
- If both are black, they go into the dealer’s pile.
- If one red and one black, both are discarded.
- At the end:
- If your pile has more cards, you win $100.
- If not (tie or dealer has more), you win nothing.
- You get to choose the entry fee before playing.
What Should You Pay?
Let’s analyze the symmetry and probability:
- The deck has 26 red and 26 black cards.
- Pairs are drawn randomly.
- Every red card that goes to you is matched by a black card that can go to the dealer.
- Whenever two red cards go to you, a black-black pair is equally likely.
Key Insight
You don’t even need to rely on probability or expected values! Let’s look at the deterministic math of every single deck:
- Every mixed pair (discarded) consumes exactly 1 red card and 1 black card.
- The remaining cards form the mono-color pairs (your pile and the dealer’s pile).
Mathematical Outcome
Let \( M \) be the number of mixed pairs. These \( M \) pairs consume exactly \( M \) red cards and \( M \) black cards from the deck.
This leaves exactly \( 26 - M \) red cards for your pile, and \( 26 - M \) black cards for the dealer’s pile.
Because your pile and the dealer’s pile will always have the exact same number of cards, the game always ends in a tie, regardless of how the deck is shuffled.
Since the rules state you only win if you have more cards, your chances of winning are exactly 0%.
Final Answer
The maximum fee you should pay is $0.
Playing this game has zero expected value—it’s a cleverly disguised losing proposition.