Brain Teasers
Liars and Truth Tellers
You approach two magic talking doors. One door leads to the City of Truth, while the other door leads to the City of Liars. You do not know which door is which. You are able to ask only one question to determine which door is which. The door that leads to the City of Liars always speaks lies, while the door that leads to the City of Truth always speaks the truth. You want to go to the City of Truth. What question do you ask to determine which door leads to the City of Truth?
Answer
Answer #1: You ask a door - "If I were to ask the other door which door leads to the city of truth, what would he say?" and then you pick the opposite door of what he tells you.Answer #2: Ask the door - "If I asked you which door leads to the city of truth before, which door would you have told me?" (negative and negative = positive, positive and positive = positive). and you choose the door that it directs you to.
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Your answer #2 would not work because if you asked the door to the city of liars that question, he would still lie and tell you the wrong one. The fact that you rephrase the question doesn't make it any different from the question. "Which door is the door to the city of truths?"
Answer #2 will also work because if he had ask the question to lier door he would have lied but if he is asking what would be his reply he will lie again and two lies will lead to truth.
Answer1:
Q: Mr. Door, if I were to ask the other door which door leads to the city of truth, what would he say?
A: (LIE) MINE!
-or-
Q: Mr. Door, if I were to ask the other door which door leads to the city of truth, what would he say?
A: (TRUTH) HIS!
Answer2:
Q: Mr. Door, what would you have told me if I had asked you which door lead to the city of truth.
A: (LIE) HIS!
-or-
Q: Mr. Door, what would you have told me if I had asked you which door lead to the city of truth.
A: (TRUTH) MINE!
How clever!
Q: Mr. Door, if I were to ask the other door which door leads to the city of truth, what would he say?
A: (LIE) MINE!
-or-
Q: Mr. Door, if I were to ask the other door which door leads to the city of truth, what would he say?
A: (TRUTH) HIS!
Answer2:
Q: Mr. Door, what would you have told me if I had asked you which door lead to the city of truth.
A: (LIE) HIS!
-or-
Q: Mr. Door, what would you have told me if I had asked you which door lead to the city of truth.
A: (TRUTH) MINE!
How clever!
Wait a minute... this is flawed.
If I asked a door, "What's my name?"
The truth sayer would either say, "I don't know" or tell me my name.
The lying one would make up a name because it couldn't admit that it didn't know. And "I'm not telling you" isn't a lie unless he actually tells me my real name shortly after.
I could stump it with Bilbo's famous riddle too. What have I in my pocket?
If I asked a door, "What's my name?"
The truth sayer would either say, "I don't know" or tell me my name.
The lying one would make up a name because it couldn't admit that it didn't know. And "I'm not telling you" isn't a lie unless he actually tells me my real name shortly after.
I could stump it with Bilbo's famous riddle too. What have I in my pocket?
yes the question is flawed ... you should state that the door that tells lies can lead to the city of truth or not and vice versa..
I've heard other variations of this teaser but this is the worst.
David Bowie was creepy in the movie "Labyrinth." Old guys and leather pants just don't work out. Eartha Kitt in leather pants, however...
Wait! I meant a YOUNG Eartha Kitt.
Doors don't talk. I've seen this teaser on the site before in a different form, hmmmm.....
How many letters are in my first name? Easy and simple question...
i would have asked what color the sky was, or what day is it.
I just thought of something! If you ask the Liars door, then they could just say "I don't know" and be lying because they really do know what the answer is.
I have definitely heard this before, but this is still a great teaser.
I have definitely heard this before, but this is still a great teaser.
Yeah....this was from labyrinth...great film....I love David Bowie....but I could go without seeing him in skin tight stretch pants
I have also heard in one form or another and don't care for this one. I also think there are many simpler questions for the door of liars to get to the truth door. Just my opinion.
weren't you just supposed to poke it with a stick and ask it if you just poked it? oh well,
I don't quite understand the second answer... it's just not making sence to me.
If you only get to ask one question, and waste the question by asking the door the number of letters in your first name or some other unrelated question, you're stuck.
"Does this door lead to your home city?" If he says yes, it's the city of truth. If he says no, it's a lie.
How about "If I ask you a question, will the other door give me the same answer as you?" The lying door says yes, the truth door says no.
This avoids having to establish any external truth to test the doors against, yet is still just a question with a known answer.
This avoids having to establish any external truth to test the doors against, yet is still just a question with a known answer.
Ask, "What's my name?" If it doesn't tell you your name, pick the other door.
I asked "am I only alowed one question?"
Why don't we just ask them something that we know true?
That would be a lot easier lol.
And it's not even written against the rule. You're just complicating things.
That would be a lot easier lol.
And it's not even written against the rule. You're just complicating things.
Virtually unlimited options. Could ask ones like "do both of you tell the truth?" Obviously the true door would answer no, the lie door answer yes.
This form of question is stolen from Mindtrap.
This form of question is stolen from Mindtrap.
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