C knows his hat is black, if his hat was white then D would have seen two white hats and yelled that his hat was black. Because D did not do this, C realized that D must be seeing 2 different hats and that his hat is therefore black.
damn i'm really tempted to look at the solution. i've been staring at the diagram and instructions for like 5 minutes and i haven't figured it out yet.
If B and Cs hats are the same color D knows that his hat is obviously the other color and can call it out. If D does not call out a color C knows his hat is a different color than the guy in front of him and can call it out.
Here is another "guess the hat" brain teaser. This time there are 10 guys buried in the ground in a line. They are all facing forward so guy #1 can see everybody's hat (but his), guy #2 can see 3-10, guy #3 can see 4-10, etc... They each have a 50/50 chance of getting either a black or white hat (so it's not necessarily 5 x black and 5 x white). They all have to guess the color of their hat. Guy #1 guesses first, guy #2 guesses second, etc...
They have time before the test to agree on a strategy. There is a strategy which will save at least 9/10 guys for sure. What is it?
This isn't a trick question. They can't give audio clues like making your guess in a high pitch or a low pitch to tell the person in front of them what hat color they have. It's a logic/math solution.
To those working it out, this is completely logical. There is no trickery at all. I know the picture says it, but it's easy to doubt that. There's nothing like "he leans forward and the hat falls off".
There are a lot of variations of this puzzle, I did a similar one back in one of my logic classes during freshman year of college. The part that irks me is that your answer relies on your compatriots (the other hat wearers) not being idiots. So that's kind of out of the question in a normal situation.
Puzzles like this make we want to be an executioner. Even if they solve it I still shoot them then go home with a big smile on my face and plow my wife.
This was quite simple but very fun. D would have noticed if he had seen two white hats and would have called out (if he had a brain in him). When C realized that D had not called out he figured he must have had the black hat.
On October 31 2009 21:11 madnessman wrote: damn i'm really tempted to look at the solution. i've been staring at the diagram and instructions for like 5 minutes and i haven't figured it out yet.
If B and Cs hats are the same color D knows that his hat is obviously the other color and can call it out. If D does not call out a color C knows his hat is a different color than the guy in front of him and can call it out.
Here is another "guess the hat" brain teaser. This time there are 10 guys buried in the ground in a line. They are all facing forward so guy #1 can see everybody's hat (but his), guy #2 can see 3-10, guy #3 can see 4-10, etc... They each have a 50/50 chance of getting either a black or white hat (so it's not necessarily 5 x black and 5 x white). They all have to guess the color of their hat. Guy #1 guesses first, guy #2 guesses second, etc...
They have time before the test to agree on a strategy. There is a strategy which will save at least 9/10 guys for sure. What is it?
This isn't a trick question. They can't give audio clues like making your guess in a high pitch or a low pitch to tell the person in front of them what hat color they have. It's a logic/math solution.
If they agree that number 1 will guess white if he sees an odd number of white hats and guess black if he sees an even number of white hats. If number 1 calls white and number 2 sees an even number of white hats he's got a white one. If he sees an odd number he's got a black one. Rinse and repeat, everyone have to remember when it's there turn if they should have an even or odd number of whites in front of them.
There's actually no correct answer to OP's puzzle, not even his own answer. + Show Spoiler +
Just because D sees 2 different colors doesn't mean that D's hat has to be white. For all he knows, A and C has white, B and D has black. Unfortunately your hat-men are left with a 50-50 guess for whomever is feeling lucky that day.
iv seen far too many of these puzzles this one took me no time at all :p + Show Spoiler +
well C can see a white hat and i assume he knows that D can see both his and B's hats. therefore C knows that D sees a white + X. if D sees white+white, he'd auto-yell black. he doesn't, because he sees white+black. C realizes this and since he's not the white (cos he can see the white) he's sure he's black
what? D's color doesn't matter, he's not the one guessing, because like you said, he can't be sure of his color cos he sees diff ones. C is the one guessing and C knows his color 100% given 2 conditions: -he knows that D can see B and C's hats -D is not an idiot
On November 01 2009 01:09 Adeny wrote: There's actually no correct answer to OP's puzzle, not even his own answer. + Show Spoiler +
Just because D sees 2 different colors doesn't mean that D's hat has to be white. For all he knows, A and C has white, B and D has black. Unfortunately your hat-men are left with a 50-50 guess for whomever is feeling lucky that day.
Your scenario doesn't matter, since it isn't D who are the one with the information he needs to tell what color his hat is, it is C. C sees that B has a white hat. The fact that D doesnt cry out tells C that he and B has different colors and since he sees that B has a white one, hence his hat is black. If he had seen a black hat in front of him and no reaction from D, he would have a white hat.
On October 31 2009 21:22 NoobsOfWrath wrote: There are a lot of variations of this puzzle, I did a similar one back in one of my logic classes during freshman year of college. The part that irks me is that your answer relies on your compatriots (the other hat wearers) not being idiots. So that's kind of out of the question in a normal situation.
puzzle should say, "this diagram shows 4 puzzle nerds buried up to their necks in sand"
it relies on D not being a retard. If I was C in that situation I would be scared as fuck to say my hat was black because I'd be worried D was just a dumbfuck tool and he didn't know what he was doing lol
On November 01 2009 01:51 -orb- wrote: I don't like this one because + Show Spoiler +
it relies on D not being a retard. If I was C in that situation I would be scared as fuck to say my hat was black because I'd be worried D was just a dumbfuck tool and he didn't know what he was doing lol
This is why its just a fun logic puzzle. If it were a real live situation I think even the smartest people when trapped up to their necks so they can't move and are about to be executed would panic and lose most of their logical reasoning. Doesn't necessarily make them "dumbfuck retarded tools".
However if this was a real life situation where there was no penalty or execution, just a 10 min time limit and people buried in the sand with hats just to try to figure out the riddle, then maybe it would be fair to call them dumb ;p
damn just spent half an hour on this. I think the answer is C. Because he knows B's hat is white. D would then have called out his hat was black, if C was white as well. However he didn't call out. Meaning he can see one white and black hat. Since B's is white. C can be 100% certain his hat is black?
On November 01 2009 03:15 DoctorHelvetica wrote: How stupid would you have to be to see two white hats and not immediately call out black. It requires D to not be blind, not to be intelligent.
agreed, you would actually have to be criminally stupid not to see the connection "2 whites and 2 black total, I see 2 white I have black". Sure there are lots of that kind of people in the world but no more than 48.3% I'd say. Btw anyone else who came up with the same solution as I did to madnessman's puzzle? Is there another way?
C knows his hat is black, if his hat was white then D would have seen two white hats and yelled that his hat was black. Because D did not do this, C realized that D must be seeing 2 different hats and that his hat is therefore black.
This was a weird one. I ran through the possibilities, and I guess "intuited" the correct answer from that but couldn't figure out *why* it was right for the longest time. I'm not sure if this makes me smart or stupid.