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March 5th, 2014, 02:48 PM   #1
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Alien Abduction Brain Teaser

Okay, here is the brain teaser.

10 people have been abducted by aliens because they view them as being representative of the human race. They are going to test them to see if the human race is worthy of entering the intergalactic council of planets and if they are not they are going to kill all the people and turn earth into a mushroom farm because that's their oil. Already sounds scary doesn't it? And so they take them in their spaceship and say "You ten represent all of humanity and the fate of humanity rests in your hands. We will give you a test and the test is tomorrow. 24 hours from right now we are going to put you all in a dark room and line you up 1 behind the other. Each person will, once the lights are turned on, be able to see only the back of the heads of the people in front of him. While the room is pitch dark we are going to place a hat on each of your heads and it will either be purple or green. The hats are designed in such a way that you can't see your own hat. The distribution of the hats will be random." They are going to start with the person in the back and ask "What color is the hat on your head?" and he has to say it with an even tone. He can, however, say it as loud as he wants. Everyone is going to hear what everyone is going to say. If you are right, you will live and all the people you represent will also live and won't be turned into a mushroom farm, but if you are wrong you will die and the people you represent will also die and the land they are on will turn into a mushroom farm. So they say "We are going to do this tomorrow and your goal is to save as many people as possible. You have 24 hours to discuss this and come up with a system so that when we put you in the dark room and we put hats on each of your heads and then turn on the lights. If any of the 10 people cheat they will kill us all and turn the whole earth into a mushroom farm." Now in the next 24 hours they come up with a system in which the person in the back counts the number of green hats only and if it is odd he will say green and if it is even he will say purple and then other people deduce the color of their hats based on what the other people say.

Like for example:
G = green
P = purple
G P P G G P G G P P
The guy in the back sees an odd number of green hats and so he will say green and get displaced.
The second guy sees an odd number of green hats and he will say purple.
and on and on and on through a binary tree with 2^1 + 2^2 + 2^3 ... + 2^9 + 2^10 branches.

Now my question is can you make this brain teaser work for any number of colors.

Like, for example, let's say we have Red, Orange, Yellow, Green, Blue, and Purple hats.

Can you make a system that branches from 1 color to the next and will save at least 9 people if not more?
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March 5th, 2014, 10:20 PM   #2
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You've copied an incorrect version of the brainteaser, as the last-mentioned utterance by the aliens is clearly incomplete. However, it's evident what you probably intended.
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March 5th, 2014, 10:42 PM   #3
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Re:

Quote:
Originally Posted by skipjack
You've copied an incorrect version of the brainteaser, as the last-mentioned utterance by the aliens is clearly incomplete. However, it's evident what you probably intended.
It is not incorrect. Khan even says so.
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March 6th, 2014, 05:01 AM   #4
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Re: Alien Abduction Brain Teaser

Well, doesn't make much sense to me.
Regardless of how accurate the plan is, the poor sucker at back of line
has only a 50% chance to survive.
Yet puzzle states that EVERYBODY dies if this guy's "color announcement" does not match his own color.

Puzzle is also badly worded and cumbersome; tell that to Khan :P
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March 6th, 2014, 08:12 AM   #5
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Quote:
Originally Posted by caters
It is not incorrect. Khan even says so.
The section beginning "So they say" contains an opening quotation mark, but there is no closing quotation mark later on, so there is definitely something missing in your version, which means that your version doesn't make sense. I haven't read Khan's version.
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March 6th, 2014, 10:05 AM   #6
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Re: Alien Abduction Brain Teaser

Quote:
Originally Posted by Denis
Well, doesn't make much sense to me.
Regardless of how accurate the plan is, the poor sucker at back of line
has only a 50% chance to survive.
Yet puzzle states that EVERYBODY dies if this guy's "color announcement" does not match his own color.

Puzzle is also badly worded and cumbersome; tell that to Khan :P
No that is if they cheat not the color not matching the color of the hat on the guy in the back.
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March 6th, 2014, 10:31 AM   #7
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Re: Alien Abduction Brain Teaser

Quote:
Originally Posted by caters
No that is if they cheat not the color not matching the color of the hat on the guy in the back.
Well, whadda heck happens if the back guy announces the color he's not wearing?!

Why don't YOU rewrite the puzzle in simple terms, making everything CLEAR?

Btw, this is a well known puzzle; here:
https://www.google.ca/?gfe_rd=cr&ei=Nsw ... s+and+hats
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March 6th, 2014, 10:51 AM   #8
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Re: Alien Abduction Brain Teaser

Quote:
Originally Posted by Denis
Quote:
Originally Posted by caters
No that is if they cheat not the color not matching the color of the hat on the guy in the back.
Well, whadda heck happens if the back guy announces the color he's not wearing?!

Why don't YOU rewrite the puzzle in simple terms, making everything CLEAR?

Btw, this is a well known puzzle; here:
https://www.google.ca/?gfe_rd=cr&ei=Nsw ... s+and+hats
The guy anounces the wrong color and he dies but the other guys deduce off of what they see and hear and are all correct. So you save 9 * 9/10 of earth that way.
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March 6th, 2014, 11:29 AM   #9
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Re: Alien Abduction Brain Teaser

Quote:
Originally Posted by caters
The guy anounces the wrong color and he dies but the other guys deduce off of what they see and hear and are all correct. So you save 9 * 9/10 of earth that way.
YES...and that's what I'm getting at.

BUT show us WHERE that's stated in the puzzle you posted.
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March 6th, 2014, 11:40 AM   #10
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Re: Alien Abduction Brain Teaser

Quote:
Originally Posted by Denis
Well, doesn't make much sense to me.

... the poor sucker ...

... tell that to Khan :P

[attachment=0:372z0he5]y8DlGLa.jpg[/attachment:372z0he5]

"Only Nixon could go to China"

"Only Rodman could go to North Korea"

"Only James Tiberius Kirk could tell it like it is to Khan"

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