Liars and Truth Tellers

[colclipper]

Here's a variation on the story I had not seen before. A man, who is dying, is in a bar. Two women are seated at a table. One always tells the truth and the other always lies. In front of the women are two glasses, one contains a drink that will cure the man, the other a poison that will kill him. What one question should he ask?

 

[daveb]

Point to drink #1 and ask woman #1, "Would woman #2 say this drink would cure me?" If the answer is no, drink that one. If she says yes, drink the other one. Not much of a variation.

 

[dav2008]

Tell both women to take a sip of their respective drink.

 

[Lisa!]

I heard the same 1 abut a prisoner and exit door.
Nice 1!

 

[daveb]

Tell both women to take a sip of their respective drink.

Yes, but you're supposed to ask one a question, not tell both of them to do something. Neither is obligated to do something, but each is obligated to always answer (since it says each always lies or always tells the truth).

 

[colclipper]

Point to drink #1 and ask woman #1, "Would woman #2 say this drink would cure me?" If the answer is no, drink that one. If she says yes, drink the other one. Not much of a variation.

That'a the best answer I've seen. I had just never heard the problem phrased in this way.