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-   -   Money or your life. (http://archives2.twoplustwo.com/showthread.php?t=21862)

Mike Haven 10-10-2002 06:15 PM

Money or your life.
 
have a go at this one, but only if you don't know it - that means not you, brucez! [img]/forums/images/icons/wink.gif[/img]

you have two doors - behind one is unlimited treasure - behind the other is certain death


each door is guarded by a sentry - one sentry always lies - one sentry always tells the truth

you can ask one sentry one question, only, before you make your choice of which door to open to the treasure

who do you ask what, and which door do you open?

BruceZ 10-10-2002 06:27 PM

Re: Money or your life.
 
have a go at this one, but only if you don't know it

How can anyone answer if they don't know it? Once you read the question and figure it out then you wouldn't qualify to answer.

I have seen this before BTW. In fact I was in grade school when I first saw it (not making fun of the problem, that's just how long ago I first saw it). I hadn't seen the last one before (aces one).

BruceZ 10-10-2002 08:22 PM

Did you leave something out?
 
Did you intend to tell us what the lying sentry is guarding and what the truthful sentry is guarding? It isn't necessary for you to tell us this, but that's how the version I know was asked. Your version is different from what I heard, but I came up with a question that would find the treasure in your problem too.

Mike Haven 10-10-2002 08:30 PM

no ...
 
no - either sentry could be guarding either door

i think we all know you are the main man in this forum, bruce - i'm just trying to handicap you with a couple of days' delay before you post the correct answer, as always!

the trouble with these threads, or at least the way i have mine set up anyway, is that while you are reading the question you can see other's answers

maybe we should use different threads for the answers?

10-10-2002 08:39 PM

I think I have it.
 
Ask either of the two doors,

"If I asked the other door which door held the treasure, which one would he tell me to pick" and then take the opposite.

If you are talking to the liar door, he will lie about the truth.

If you are talking to the truth door, he will tell the truth about the liar.

BruceZ 10-10-2002 09:43 PM

Re: no ...
 
the trouble with these threads, or at least the way i have mine set up anyway, is that while you are reading the question you can see other's answers

maybe we should use different threads for the answers?


We could post answers in a different thread, but if you don't want to see answers all you have to do is click on the link that says "threaded" before you read the question. You don't have to change your settings.

10-10-2002 11:32 PM

Just put Ans or Solution in the Subject *NM*
 

brad 10-11-2002 02:31 AM

Re: I think I have it.
 
amazing how adding a level of indirection always helps [img]/forums/images/icons/smile.gif[/img]

Mike Haven 10-11-2002 04:14 AM

Re: I think I have it.
 
you are the man, huh [img]/forums/images/icons/cool.gif[/img]

BruceZ 10-11-2002 09:16 AM

Re: I think I have it.
 
Another solution would be to say to either sentry "if the truthful sentry had to guard the treasure, and the lying sentry had to guard the certain death, which door would you have to guard?". Then pick the door he says.


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