Can you guess this riddle?

So there are two doors and one door leads to freedom, one leads to death. You don't know which door is which.

Two guardians guard the doors. One always tell lies and the other always tells the truth. What question can you ask to find out which door is which? You can't open the door till you absolutely know which is which

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RealtaReoite · 61-69, M

Ask either guard: "If I were to ask you if your door leads to freedom, would you say 'yes'?

If he says "yes", go that way. If he says "no", go the other way.

Tanner07 · M

@RealtaReoite: the thing is you don't know if he is lying or telling he truth.

RealtaReoite · 61-69, M

@Tanner07: It doesn't matter. It works either way.

Tanner07 · M

@RealtaReoite: no it doesn't. If he is lying if he says no than you can't tell. If he says yes you still can't tell. So yes it does matter

RealtaReoite · 61-69, M

Suppose he's a truth teller and it's the door to freedom, he'll say "yes", right? All good. Go that way.

Or if he's a truth teller, and it's the door to death, he'll say "no". So go the other way.

Now, suppose he's a liar and it's the door to freedom. If I asked him if it's the door to freedom, he'd lie and say "no". But I didn't ask him that. I asked him "IF I ASKED YOU if that's the door to freedom would you say "yes"? but we just established that his answer to the direct question would be "no". But since he's a liar, he'd say "yes" to the actual question I asked. And that would be the way to do.

The last case is left as an exercise to the reader.

Tanner07 · M

@RealtaReoite: oh... well that wasn't the answer I came up with... I just simpley asked is he was a guard. Boom. We found our liar

RealtaReoite · 61-69, M

Oh, I assumed you could only ask one question. With two, that would work fine.