Jump to content


Welcome to BrainDen.com - Brain Teasers Forum

Welcome to BrainDen.com - Brain Teasers Forum. Like most online communities you must register to post in our community, but don't worry this is a simple free process. To be a part of BrainDen Forums you may create a new account or sign in if you already have an account.
As a member you could start new topics, reply to others, subscribe to topics/forums to get automatic updates, get your own profile and make new friends.

Of course, you can also enjoy our collection of amazing optical illusions and cool math games.

If you like our site, you may support us by simply clicking Google "+1" or Facebook "Like" buttons at the top.
If you have a website, we would appreciate a little link to BrainDen.

Thanks and enjoy the Den :-)
Guest Message by DevFuse
 

Photo
- - - - -

Hats on a death row!! One of my favorites puzzles!


Best Answer bonanova, 08 January 2008 - 06:25 PM

Spoiler for Here's my idea
Go to the full post


  • Please log in to reply
471 replies to this topic

#41 roolstar

roolstar

    Advanced Member

  • Members
  • PipPipPip
  • 250 posts
  • Gender:Male

Posted 19 February 2008 - 10:40 PM

This is an awesome riddle btw :D I voted 5 stars ;D


Thank you...
I apreciate it!

Especially coming from a PUZZLE MASTER...

And by the person who set the voting rules too!!! :)

Edited by roolstar, 19 February 2008 - 10:47 PM.

  • 0

#42 thebrain

thebrain

    Newbie

  • Members
  • Pip
  • 13 posts

Posted 21 February 2008 - 05:55 PM

If you don't already know this one, I'm sure you will find it very interesting and fun to solve! And if you do find the answer (or already know it) please put it under a spoiler tab so that you don't take the fun from the rest of the intelligent people in this forum....

Here we go....

You are one of 20 prisoners on death row with the execution date set for tomorrow.

Your king is a ruthless man who likes to toy with his people's miseries. He comes to your cell today and tells you:

“I’m gonna give you prisoners a chance to go free tomorrow. You will all stand in a row (queue) before the executioner and we will put a hat on your head, either a red or a black one. Of course you will not be able to see the color of your own hat; you will only be able to see the prisoners in front of you with their hats on; you will not be allowed to look back or communicate together in any way (talking, touching.....)

(The prisoner in the back will be able to see the 19 prisoners in front of him
The one in front of him will be able to see 18…)

Starting with the last person in the row, the one who can see everybody in front of him, he will be asked a simple question: WHAT IS THE COLOR OF YOUR HAT?

He will be only allowed to answer “BLACK” or “RED”. If he says anything else you will ALL be executed immediately.

If he guesses the right color of the hat on his head he is set free, otherwise he is put to death. And we move on to the one in front of him and ask him the same question and so on…

Well, good luck tomorrow, HA HA HA HA HA HA!”

Now since you all can communicate freely during the night, can you find a way to guarantee the freedom of some prisoners tomorrow? How many?

ok this may sound weird but there is a chance from 0 or 20 you see if the king is really cruel he could have but white hats on there heads therfore a possibility of 0 living or he might not be that cruel and may i remind you if one person answers wrong they all die soe that makes it impossible for 19 to live or does it? :unsure:
  • 0

#43 roolstar

roolstar

    Advanced Member

  • Members
  • PipPipPip
  • 250 posts
  • Gender:Male

Posted 21 February 2008 - 06:40 PM

ok this may sound weird but there is a chance from 0 or 20 you see if the king is really cruel he could have but white hats on there heads therfore a possibility of 0 living or he might not be that cruel and may i remind you if one person answers wrong they all die soe that makes it impossible for 19 to live or does it? :unsure:


I'm not sure I follow you there... RED PART
Even if he puts white hats on all their heads, they can still use the technique that we figured out on this forum and survive. (at least 19 of them)

GREEN PART
If the king tells each prisoner if he got the right answer or not just after they answer, the rest can still reason and survive...

Example:
Prisoner 10 screws up and says the wrong color (BLACK for example), the king tells him that he got it wrong and that he's gonna die, prisoner 9 can continue the reasonning after considering that Prisoner 10 had a WHITE hat and survive, the rest will follow...
  • 0

#44 hopstop

hopstop

    Newbie

  • Members
  • Pip
  • 19 posts

Posted 21 February 2008 - 07:43 PM

cant the first person tell the person in front what colour hat they are wearing and so on... then so long as they are all truthfull all should be saved exept the first one who only has a 50/50 chance.
  • 0

#45 bonanova

bonanova

    bonanova

  • Moderator
  • PipPipPipPip
  • 5917 posts
  • Gender:Male
  • Location:New York

Posted 21 February 2008 - 08:38 PM

cant the first person tell the person in front what colour hat they are wearing and so on... then so long as they are all truthfull all should be saved exept the first one who only has a 50/50 chance.

A person dies unless he speaks the color of his own hat.
Saying the color of the hat of someone else could get him killed... ;)
  • 0
The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

#46 roolstar

roolstar

    Advanced Member

  • Members
  • PipPipPip
  • 250 posts
  • Gender:Male

Posted 21 February 2008 - 09:07 PM

cant the first person tell the person in front what colour hat they are wearing and so on... then so long as they are all truthfull all should be saved exept the first one who only has a 50/50 chance.


This technique saves 10 prisoners for sure and the rest will have 50/50 chances...
  • 0

#47 FERG

FERG

    Newbie

  • Members
  • Pip
  • 2 posts

Posted 14 March 2008 - 09:29 PM

as far as i'm aware this puzzle requires there to be equal numbers of red and black hats, though this is a variation on the one i know so that may not be so
  • 0

#48 mcgiverr

mcgiverr

    Newbie

  • Members
  • Pip
  • 4 posts

Posted 17 March 2008 - 02:45 PM

My method will save a minimum of 10 people, mabe more.
The last man calls out the colour of number 1's hat, 19 calls out the colour of 2's hat and so on. The firts 10 will then know the colour of their hats and 11 to 20 have a 50/50 chance of getting their own colour correct.
  • 0

#49 Duh Puck

Duh Puck

    Advanced Member

  • Members
  • PipPipPip
  • 445 posts

Posted 17 March 2008 - 02:50 PM

Even if he puts white hats on all their heads, they can still use the technique that we figured out on this forum and survive. (at least 19 of them)

I don't think so. I think the white hat trick is a pretty twisted but surefire way to ensure mass execution, since, according to the rules ...

He will be only allowed to answer “BLACK” or “RED”. If he says anything else you will ALL be executed immediately.

Glad that sicko isn't my king. :P
  • 0

#50 ALFRED

ALFRED

    Junior Member

  • Members
  • PipPip
  • 54 posts

Posted 18 March 2008 - 06:36 PM

awesome puzzle roolstar. I want to get a group of friends together and try it to see if we're smart enough to save ourselves.
  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users