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To: The Philosopher who wrote (21344)11/22/2001 4:53:54 PM
From: The Philosopher  Read Replies (4) | Respond to of 62549
 
Okay, here's another one for y'all.

Three sisters, Annie,k Betty, and Cassie, can eithe rlie or tell the truth. (that is, they're human!).

They have two playing cards, the Ace of Spades and the King of Spades. One of the sisters takes one of these cards and puts it behind her back. The others put their hands, empty, behind their backs. They all walk into the room and face you so you can't see their hands.

If the card is the King, the sister who is holding it MUST tell the truth. If the card is the Ace, teh sister who is holding it MUST lie. Those not holding the card can lie or tell the truth, as they choose.

They make the statements as follows:
Annie: I have the card.
Betty: I do not have the card.
Cassie: Annie does not have the card.

At most, one of these statements is true. That is, either two or all three are false. Who has the card, and what is it?



To: The Philosopher who wrote (21344)11/22/2001 5:51:42 PM
From: Ish  Respond to of 62549
 
So now we have 3 solutions that all work.



To: The Philosopher who wrote (21344)11/23/2001 1:07:00 PM
From: Bargain Hunter  Respond to of 62549
 
The original statement of the problem did not indicate whether the guards were aware of each other's compulsion to tell the truth or lie. So the "what would you say if I asked you" approach is to be preferred over the "what would the other guard say if I asked him" approach.