Two players put one dollar into a pot. They decide to throw a pair of ...
Understanding the Game
In this game, players alternate throwing a pair of dice. The first to roll a sum of 5 wins the pot. Each player contributes one dollar initially, so the pot starts at two dollars.
Winning Probability
- The possible outcomes when rolling two dice are 36.
- The combinations that sum to 5 are: (1,4), (2,3), (3,2), (4,1) — a total of 4 favorable outcomes.
- Thus, the probability of rolling a sum of 5 is 4/36 = 1/9.
Player Probabilities
- Player 1's Turn: Player 1 goes first.
- Probability of winning on the first roll: 1/9.
- Probability of not winning: 8/9.
- Player 2's Turn: If Player 1 does not win, Player 2 rolls.
- Player 2's probability of winning is also 1/9, but only if Player 1 didn’t win.
- The game can continue in rounds until one wins.
Calculating Fairness
- Let P1 be the probability that Player 1 wins eventually.
- P1 = (1/9) + (8/9)(8/9)P1, where (8/9)(8/9) represents the scenario where both players fail to win in their first turns.
- Solving gives P1 = 9/17 and P2 = 8/17 for Player 2.
Fair Game Contribution
- The pot is currently $2.
- To make it fair, Player 1 should add an additional amount to balance the expected winnings.
Expected Value Calculation
- Player 1’s expected value: (9/17) * (2 + x) - (8/17) * x = 0.
- Solving gives x = $1. Therefore, Player 1 should add $1.
Conclusion
To ensure fairness in this game, Player 1 should add $1 to the pot, making it a total of $3.