Which Door Holds the Gold?

[ashishsinghal]

There are two doors - one has lots of gold. You want to get gold . There are two guards (one for each door). Both of them know behind which door gold is kept. One guard always says the truth while the other always lies. You do not know who says the truth or who lies.
But the guards know who lies and who speaks truth. You can ask only one question. What would that be?

 

[ashishsinghal]

Please read this before answering.


https://www.physicsforums.com/showthread.php?t=100534

 

[micromass]

That's a classic one

Spoiler

What would the other guard tell you if I asked him "After which door is the gold?"?
Then pick the opposite door...

Here's a nice variants:

There are three doors, and there are three guards: one always speaks the truth, one always lies, and one randomly lies and speaks the truth. Furthermore, the speak in an unknown language, so you won't know what is yes and what is no.
You can ask three questions before deciding which door leads to the gold. Which questions would you ask?

 

[disregardthat]

There are three doors, and there are three guards: one always speaks the truth, one always lies, and one randomly lies and speaks the truth. Furthermore, the speak in an unknown language, so you won't know what is yes and what is no.
You can ask three questions before deciding which door leads to the gold. Which questions would you ask?

This is nearly an impossible puzzle, it's the hardest logic puzzle ever!

 

[LudusRex]

I would approach this situation by first considering the information given. It is clear that there are two doors, one with gold and one without. Additionally, there are two guards, one who always tells the truth and one who always lies. It is important to note that the guards know each other's nature and are aware of which door holds the gold.

In order to determine which door holds the gold, I would ask one of the guards the following question: "If I were to ask the other guard which door holds the gold, what would they say?" This question allows me to gather information from both guards without directly asking them which door holds the gold.

If I ask the truthful guard, they would honestly tell me what the lying guard would say, which would be the incorrect door. If I ask the lying guard, they would lie about what the truthful guard would say, also leading me to the incorrect door. However, by knowing that both guards know each other's nature, I can deduce that the opposite door of their response is the one that holds the gold.

Ultimately, as a scientist, I would use logic and reasoning to approach this problem and determine the correct door that holds the gold. The key is to ask a question that allows me to gather information from both guards, while also considering their deceptive natures.