The riddle thread

[Hamish Durie]

pretty basic title post a riddle and if you know the answer to a riddle already posted quote him/her with the answer

pretty easy one
why

 

[Liudeius]

To answer you, Because.

This is courtesy of XKCD (as in I ripped it straight from their site), it's one of my favorite riddles.

Blue Eyes:
The Hardest Logic Puzzle in the World

A group of people with assorted eye colors live on an island. They are all perfect logicians -- if a conclusion can be logically deduced, they will do it instantly. No one knows the color of their eyes. Every night at midnight, a ferry stops at the island. Any islanders who have figured out the color of their own eyes then leave the island, and the rest stay. Everyone can see everyone else at all times and keeps a count of the number of people they see with each eye color (excluding themselves), but they cannot otherwise communicate. Everyone on the island knows all the rules in this paragraph.

On this island there are 100 blue-eyed people, 100 brown-eyed people, and the Guru (she happens to have green eyes). So any given blue-eyed person can see 100 people with brown eyes and 99 people with blue eyes (and one with green), but that does not tell him his own eye color; as far as he knows the totals could be 101 brown and 99 blue. Or 100 brown, 99 blue, and he could have red eyes.

The Guru is allowed to speak once (let's say at noon), on one day in all their endless years on the island. Standing before the islanders, she says the following:

"I can see someone who has blue eyes."

Who leaves the island, and on what night?


There are no mirrors or reflecting surfaces, nothing dumb. It is not a trick question, and the answer is logical. It doesn't depend on tricky wording or anyone lying or guessing, and it doesn't involve people doing something silly like creating a sign language or doing genetics. The Guru is not making eye contact with anyone in particular; she's simply saying "I count at least one blue-eyed person on this island who isn't me."

And lastly, the answer is not "no one leaves."

I've done my best to make the wording as precise and unambiguious as possible (after working through the explanation with many people), but if you're confused about anything, please let me know. A word of warning: The answer is not simple. This is an exercise in serious logic, not a lateral thinking riddle. There is not a quick-and-easy answer, and really understanding it takes some effort.

Here's the link to the page I copied it from [link]http://xkcd.com/blue_eyes.html[/link]

People seem to be misunderstanding it. The guru only speaks one sentence, one time in her entire life.

EDIT 2:
Your blue eyes riddle is damm hard...
I have no idea D:

pleasepleaseplease answer to that xkcd riddle i'm busting by brains over that one.

I guess it has to do with serious deduction.

If you absolutely MUST know, and would prefer the shame of defeat, you can always look it up online.
I didn't notice I could just search it on the internet until a year after I heard it. (That's ironic...) Fortunately it only took me half an hour to solve.
I'll give you a hint, only open the spoiler if you are really stuck, it nearly solves the riddle for you.

Spoiler: Blue Eyes Hint

Think of it in a smaller scale. What would happen if only one person had blue eyes and the rest brown?

And if you absolutely must cheat, at least cheat with a reputable source [link]http://xkcd.com/solution.html[/link]

Avistew made the first correct answer.

Spoiler: Other Posted Riddles

If a tree falls down in the woods and noone is there to hear it, does it still make a sound?

First off, did you know none is actually a shortening of no one? It can be plural or singular. Noone is certinaly not proper English though...

And to answer you, yes. This is not some deep question or some scientific thought experiement, it's just a stupid question carried on by similarly inclined (and "deep" [but not really]) people.
Sound is the vibration of particles, traveling in waves, none need hear it for it to exist. A deaf man screaming still has a voice, it doesn't matter if he's alone in the middle of a desert.
Just because you can't see light waves traveling through space doesn't mean they aren't there,
just because you don't have a receiver to pick up radio waves doesn't mean they don't exist,
just because you aren't there to hear sound waves doesn't make them any less real.

A man builds a house with all four walls facing south and when he looks out of his window he can see a bear, where did the man build his house?

I suppose I shouldn't answer EVERY riddle, so I'll just say, is south supposed to influence their answer so it becomes wrong even when they use the proper thought process?

What is the beginning of eternity,
The end of time and space?
What is the beginning of every end,
And the end of time and space?

More... Riddles... Must... Answer.. GAH!

 

[Mojo]

If a tree falls down in the woods and noone is there to hear it, does it still make a sound?

 

[standokan]

If a tree falls down in the woods and noone is there to hear it, does it still make a sound?

Well that depends, if by sound you.. wait a minute, are you being philosophical?

OT: A man builds a house with all four walls facing south and when he looks out of his window he can see a bear, where did the man build his house?

 

[Belisarius^_^]

What is the beginning of eternity,
The end of time and space?
What is the beginning of every end,
And the end of time and space?

Try to read it in the literal way...

I found this one in an android game called craniati enigma. It gives you all kind of riddels like this one but also riddels of which the anwsers are hidden inside your phone or in the way you use your phone. Greate game, even tough i got stuck afer 20 questions

 

[GenericAmerican]

Whoever makes it, tells it not. Whoever takes it, knows it not. And whoever knows it wants it not.

 

[exarkunsith]

What is the beginning of eternity,
The end of time and space?
What is the beginning of every end,
And the end of time and space?

Try to read it in the literal way...

I found this one in an android game called craniati enigma. It gives you all kind of riddels like this one but also riddels of which the anwsers are hidden inside your phone or in the way you use your phone. Greate game, even tough i got stuck afer 20 questions

The letter E

 

[Mojo]

Oh, and to answer you, because.

If a tree falls down in the woods and noone is there to hear it, does it still make a sound?

First off, did you know none is actually a shortening of no one? It can be plural or singular. Noone is certinaly not proper English though...

Im from germany and I did not know that, but thanks for correcting me!

And to answer you, yes. This is not some deep question or some scientific thought experiement, it's just a stupid question carried on by similarly inclined (and "deep" [but not really]) people.
Sound is the vibration of particles, traveling in waves, none need hear it for it to exist. A deaf man screaming still has a voice, it doesn't matter if he's alone in the middle of a desert.
Just because you can't see light waves traveling through space doesn't mean they aren't there,
just because you don't have a receiver to pick up radio waves doesn't mean they don't exist,
just because you aren't there to hear sound waves doesn't make them any less real.

That was more of a silly/fun riddle .... I wasnt trying to be super serios about it.
I got the riddle from the simpsons btw...
Lisa asks Bart this at one point.
Dont need to get all worked up about it.

EDIT:
It even has a wiki page:
http://en.wikipedia.org/wiki/If_a_tree_falls_in_a_forest
it that you can read:

"The magazine Scientific American corroborated the technical aspect of this question, while leaving out the philosophic side, a year later when they asked the question slightly reworded, "If a tree were to fall on an uninhabited island, would there be any sound?" And gave a more technical answer, "Sound is vibration, transmitted to our senses through the mechanism of the ear, and recognized as sound only at our nerve centers. The falling of the tree or any other disturbance will produce vibration of the air. If there be no ears to hear, there will be no sound."

EDIT 2:
Your blue eyes riddle is damm hard...
I have no idea D:

 

[Liudeius]

If a tree falls down in the woods and noone is there to hear it, does it still make a sound?

That was more of a silly/fun riddle .... I wasnt trying to be super serios about it.

Oh yeah, sorry, I wasn't trying to insult you, I just know some people who take that question way too seriously. Philosophy has it's place, but not in such obvious questions.

 

[Annoying Turd]

pleasepleaseplease answer to that xkcd riddle i'm busting by brains over that one.

I guess it has to do with serious deduction.

 

[Liudeius]

Nooo, the riddle thread must not die.

I have issue with the answer to this one, but I'll post it anyway.

There is a kingdom in which once poisoned, you can be cured by taking a more lethal poison (with no ill-effects).

The king, not wanting to be in danger of being poisoned, orders the best alchemist in the land and the best thinker in the land to create the strongest poisons they can. After coming up with the best poisons they can, the king will have them each take the other's poison, then their own, so the one who made the strongest poison lives. (leaving the strongest poison in the land in possession of the king)

Knowing the alchemist can make a stronger poison, the thinker comes up with a way to live through the competition. On the day of the testing, the alchemist dies, and the king doesn't get what he wanted.

What did the thinker do?

As I said, I have issue with this one. There are multiple answers which I feel could be correct, and "strongest" isn't really defined. I would assume strongest means "that which can kill with the smallest amount consumed," but that opens up a whole 'nother line of issues with this riddle.

 

[kane.malakos]

Nooo, the riddle thread must not die.

I have issue with the answer to this one, but I'll post it anyway.

There is a kingdom in which once poisoned, you can be cured by taking a more lethal poison (with no ill-effects).

The king, not wanting to be in danger of being poisoned, orders the best alchemist in the land and the best thinker in the land to create the strongest poisons they can. After coming up with the best poisons they can, the king will have them each take the other's poison, then their own, so the one who made the strongest poison lives. (leaving the strongest poison in the land in possession of the king)

Knowing the alchemist can make a stronger poison, the thinker comes up with a way to live through the competition. On the day of the testing, the alchemist dies, and the king doesn't get what he wanted.

What did the thinker do?

As I said, I have issue with this one. There are multiple answers which I feel could be correct, and "strongest" isn't really defined. I would assume strongest means "that which can kill with the smallest amount consumed," but that opens up a whole 'nother line of issues with this riddle.

Is it that he drinks poison before the competition, and his "poison" is just water?

 

[Liudeius]

* Aforementioned Alchemist riddle*

Is it that he drinks poison before the competition, and his "poison" is just water?

Yes, I don't like it. Cheater.

 

[snowpuppy]

the pole, i win, that's a polar bear.

 

[SckizoBoy]

Blue Eyes Riddle

Took me a while to get it but:

Spoiler: Answer

EDIT: All the blue eyed leave on the 100th night, all the brown eyed leave on the 200th night.

 

[Liudeius]

Blue Eyes Riddle

Took me a while to get it but:

Spoiler: Answer

Everyone leaves on the 100th night (except the Guru)

No.

Edit:
Still no, She only says the one sentence one time.

Spoiler: Answer

The brown eyed people never leave.

 

[Avistew]

The blue eye riddle:

Spoiler

all the blue eyed people leave on the 100th day, when the Guru says for the 100th time that they see someone with blue eyes (and since they all see 99 of them only, they must be the 100th).
As a result, seeing that all the blue-eyed people are leaving, all the remaining ones know they don't have blue eyes. It would be enough for them to leave too if the choice was only between brown and blue, but you said as far as they know they might have red eyes. So if the Guru starts over with brown eyes I guess it will take another 100 days?

EDIT: The Guru needs to be talking about a different person every time, right? If they aren't it could always be the same person with blue eyes...
Does she have to stand between all the islanders? Otherwise they could just stand one by one in front and she'd have to tell them their eye colour Or some could turn away from her or something so she can't see their eyes.