Tuesday Teaser #26
This is perhaps my favourite brainteaser of all time. Whilst the solution is readily available on Wikipedia, it’s worth spending some time thinking about as the solution is both beautifully simple and counter-intuitive. Here goes:
There are five rational pirates, A, B, C, D and E. They find 100 gold coins in a treasure chest and must decide how to distribute them.
The pirates have a strict order of seniority: A is superior to B, who is superior to C, who is superior to D, who is superior to E.
The pirates’ rules of distribution are thus: that the most senior pirate should propose a distribution of coins. The pirates, including the proposer, then vote on whether to accept this distribution. If the proposed allocation is approved by a majority or a tie vote, it happens. If not, the proposer is thrown overboard from the pirate ship and dies, and the next most senior pirate makes a new proposal to begin the system again.
Pirates base their decisions on three factors. First of all, each pirate wants to survive. Secondly, each pirate wants to maximize the number of gold coins he receives. Thirdly, each pirate would prefer to throw another overboard, if all other results would otherwise be equal.
What distribution should Pirate A propose to ensure that he survives and to maximize his share?
