The Split Deal

The prisoner's dilemma played as a story: two thieves, separate rooms, and one offer each.

Ada and Bo are held in separate rooms and each offered the same deal: testify and your own sentence is wiped. Silent together they serve 1 year each; both testifying costs 8 each; one testifying while the other stays silent frees the talker and costs the silent one 10. The story shows the full payoff matrix, then asks what each one does. You type a guess, lock it in, and step through the answer and breakdown.

Why quant interviews test this

Interviewers use this to check you can find a dominant strategy case by case and attach the terms 'dominant strategy' and 'Nash equilibrium' to the right cells. The written solution at /brain-teasers/prisoners-dilemma/solution covers what breaks the trap.

The The Split Deal guide covers how scoring works, the strategy that wins, a worked example and the mistakes most players make.

More Brain Teasers games

• Screwy Pirates - Five rational pirates vote on how to split 100 gold coins, and you work out the split by backward induction from a one-pirate crew up.
• Tiger and Sheep - A hundred rational tigers and one sheep on a magic island, where any tiger that eats becomes a sheep itself - solved by induction on parity.
• Stag or Hare - The stag hunt as a story: two equilibria, and a choice that comes down to trust.
• One Offer, No Discussion - The ultimatum game as a story: one split of 100 pounds, one accept-or-reject, no negotiation.
• The Growing Pot - The centipede game as a story: a pot that doubles on every pass, and logic that says take it immediately.
• Two-Thirds of the Room - The Keynesian beauty contest as a story: pick the number closest to two-thirds of the room's average.
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