Monday, 13 February 2012

Women Or Tigers? — Solution to Third Challenge

The prisoner got it right this time as well, even though the challenge had become a little trickier. This was the logic that made him make the right choice:

As the two signs say exactly the same thing, they are either both true or both false. This means there must be a woman in one of the rooms and a tiger in the other — according to the instruction given by the king for this day’s two challenges.

If there is a woman in Room I, its sign tells the truth. If the sign tells the truth, there is also a woman in Room II. And if there is a woman in Room II, the sign on its door tells a lie. So that is not possible.

Ergo, Room I must contain a tiger. This fits with the sign on its door telling a lie. Also, as there must be a woman in Room II, it fits that that sign tells the truth.

So Room II it is! But what about the next prisoner’s challenge? It’s one of the king’s favourite challenges, so check it out. Tomorrow.

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