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Masters of Logic Puzzles I. (dots)


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#51 cd41

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Posted 17 May 2008 - 06:34 PM

Masters of Logic Puzzles I. (dots) - Back to the Logic Puzzles
Three masters of logic wanted to find out who was the wisest one. So they invited the grand master, who took them into a dark room and said: "I will paint each one of you a red or a blue dot on your forehead. When you walk out and you see at least one red point, raise your hands. The one who says what colour is the dot on his own forehead first, wins." Then he painted only red dots on every one. When they went out everybody had their hands up and after a while one of them said: "I have a red dot on my head."
How could he be so sure?


Spoiler for Solution



makes sense when u think about it
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#52 Bree

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Posted 20 May 2008 - 10:48 PM

Masters of Logic Puzzles I. (dots) - Back to the Logic Puzzles
Three masters of logic wanted to find out who was the wisest one. So they invited the grand master, who took them into a dark room and said: "I will paint each one of you a red or a blue dot on your forehead. When you walk out and you see at least one red point, raise your hands. The one who says what colour is the dot on his own forehead first, wins." Then he painted only red dots on every one. When they went out everybody had their hands up and after a while one of them said: "I have a red dot on my head."
How could he be so sure?


Spoiler for Solution

much simpler!!
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#53 beckey

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Posted 27 June 2008 - 03:06 PM

yep. i love these. there are so many variations, all are fun!


what would be funny is if the guy that yelled out "red!" actually had a blue dot, and another logician had already deduced that he himself had a red dot because he sees one blue and one red and the guy with red is raising his hand, meaning he sees ANOTHER red, which has to be the logician with red. But get this: what if that logician says nothing on purpose, so the logician with blue says "i know they're smart, they can quickly find out their own dots are red if mine was blue, but they are silent, so mine is red."

he shouts red and gets decapitated, and the other logicians grin cuz they hated him and were silent on purpose ;D

lol


yes but if you have blue on you head you wont see it will you? i believe that it is a matter of patience, the one who is the most patient will not walk away after a while and then the wiser sees that the other still raises his hand but the fairer solution is also very good
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#54 Coherence

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Posted 08 August 2008 - 01:53 AM

I had a more linguistic answer; the other two were women "wise masters" were women.

Since the grand master said, "The one who says what colour is the dot on his own forehead first, wins," and the problem ends with, "How could he be so sure?" I thought it was on of those lateral thinking questions which assaults the assumption of gender archetypes.

When I saw the length of the solution (only a glimpse) I figured my solution wasn't the right one :unsure: ...so I'll keep at it.
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#55 beavwoop

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Posted 10 November 2008 - 11:02 PM

I like This solution. The Grand - Master would make it a fair test and the only way to make it fair is paint all 3 with the same colour. The best logician would deduce this and could shout his colour out in the darkened room.

The most devious of the 3 would touch the paint with his finger, while it is wet and and look at his finger in the light and see what colour is on his hand.


you cant see the other logicans in the darkroom and looking at your finger would be cheating.

Spoiler for easy answer
:blush:
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#56 logicalist

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Posted 20 November 2008 - 10:26 PM

Spoiler for or

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#57 nihil

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Posted 23 November 2008 - 08:44 PM

What if one, taking advantage of the fact that he knew that if only one dot was red, the bearer of that dot is bound to lose, eliminating that possibility, and knowing that all dots must red, came out with his eyes closed, and, after a pause, opened them to see both opponents with their hands in the air before announcing that his one was...That would eliminate the possibility of the others deducting the answer first. This would be wise, but only if all dots weren't blue. In any fair scenario the answer would be based on the speed of reaction of each man. The grand master would only have thought up the longest scenario.
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#58 scyano

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Posted 28 September 2009 - 08:30 PM

i got it i think.....there are 3 ppl and so one of them will have a blue dot.......therefore the third person must have either a red or a blue dot.....this means that one of the three people will be seeing two ppl with the same colour....and since according to the question the person shouts out red it means that the other two had blue dots on their forehead and so he had to have the red dot....THIS SOLUTION IS VALID ONLY IF ALL THREE DOTS ARE NOT OF THE SAME COLOUR.
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