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On April 19 2012 03:52 Bubris wrote:
Don't think this has been posted, the best one I know:
3 men travel to Africa for work, they live and work together for around 2 years. At some point they decide to go see the wilds, and unfortunately on the trip, they're caught by a tribe of cannibals.
The Cannibals prepare a feast with the 3 men as the main course, but as they're about to be cooked one of the men asks the chief of the tribe to please let them live.
The chief agrees to give them one chance, but to live they have to solve a riddle.
He shows them a bag containing five hats, 2 black and 3 red. He then places the the three men on a line so that and places a hat on top of each of them so that:
The man in front can't see any of the hats
The man in the middle can see the man in front's hat
And the man in the back can see the hats of the two others.
None of them can see the color of their own hat.
The chief tells them that if one of them can tell what color hat they're wearing, they will all be freed.
Time passes and no one says anything for a looooooong time. When hours have passed the chief says "ok, last chance is now, otherwise we'll eat you". The guy standing in front then steps forward and says "I know the color of my hat"
What color is his hat?
+ Show Spoiler +easy! Ok so if the two in the front were both wearing black, the one in the black would have known he had red and would have said so. But he hasn't said anything so they are either wearing a red and a black or two reds. Now the one in the middle knows this too, and he sees the hat in front of him and knows that if it is black then since the guy in the back hasn't said anything his hat must be red. But he hasn't said anything because the color of the hat infront of him is red. So the guy at the front knows that neither of the two behind him are sure and therefor knows his hat is red.
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On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25?
+ Show Spoiler +1. The word heavy.
2. His eyes. tongue, mouth.
3. None.
4. ?
5. once
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On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25?
#5
+ Show Spoiler +
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On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25?
Question 2:
+ Show Spoiler +
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On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25?
3 and 5:
+ Show Spoiler +
Has anyone come up with the right answer for riddle number two yet? I've been thinking about it for a while now and I can only come up with lame explanations that don't seem "right".
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On April 19 2012 00:34 Mentalizor wrote:Don't know if you know this - but a teacher told it to me 7 years ago. So it's probably ancient. So here goes: (it was another currency but in order not to confuse too much, let's use dollars) The riddle:+ Show Spoiler +3 men enter a bar. They order 3 beers that all cost 10$, so the men give the waitress 30$.
However when she goes up to the bartender and tells him to get 3 beers and hands over the 30$ he says: Oh no, we have a special offer with 3 beers for 25$. So now the waitress has to go back with 5$. But you can't split 5$ into 3. So she takes 2$ for herself and hands the gentlemen their beers and 1$ each.
So this adds up. Doesn't it? Or wait... Now they all paid 9$ - so 9$ * 3 = 27$... And the waitress took 2$ for herself. That's 29$. Where did the last dollar go? [b] Hope you liked it 
+ Show Spoiler +
The waitress is handing them back 3 dollars and charging them 25 for drinks. that equals 28 dollars and a 2 dollar tip. This becomes confusing when you try to subtract 3 dollars from the 30 (which is also accurate, they paid 27 dollars, 25 for drinks and 2 for girl) and then divide that by 3. The numbers are close enough that people don't realize that 25/3 is 8.33 which when you add .66x3 (2) you get the 9 dollars that they paid.
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On April 19 2012 04:34 Shraft wrote:Show nested quote +On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25? 3 and 5: + Show Spoiler +Has anyone come up with the right answer for riddle number two yet? I've been thinking about it for a while now and I can only come up with lame explanations that don't seem "right".
Number 2 has to be that it was daytime, as mentioned above. Couldn't imagine it being anything else
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On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25?
4:
+ Show Spoiler +
new door is an anagram of one word
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On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25?
+ Show Spoiler +
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On April 19 2012 04:42 tw!tch wrote:Show nested quote +On April 19 2012 04:34 Shraft wrote:On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25? 3 and 5: + Show Spoiler +Has anyone come up with the right answer for riddle number two yet? I've been thinking about it for a while now and I can only come up with lame explanations that don't seem "right". Number 2 has to be that it was daytime, as mentioned above. Couldn't imagine it being anything else
Oh yeah... Somehow I didn't think of that. ._.
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Actually, all of the correct answers have been given so far, just not all in the same posts. See spoilers above if you want some hints/answers.
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On April 19 2012 05:14 Go1den wrote:
Actually, all of the correct answers have been given so far, just not all in the same posts. See spoilers above if you want some hints/answers.
+ Show Spoiler +ton
lol'd IRL when I had it, it was right there the whole time
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On April 19 2012 05:14 Go1den wrote:
Actually, all of the correct answers have been given so far, just not all in the same posts. See spoilers above if you want some hints/answers.
On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25?
+ Show Spoiler +1. The word "ton"
2. It's daytime
3. None (it's a hole)
4. It's an anagram
5. Only once (then it's 20)
Had these but didn't want to copy everyone else -____-
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Okay, I have a really good one. Credit goes to the xkcd forums. I'll post the answer tomorrow. The solution is extremely counterintuitive.
There are 200 people on an abandoned island. 100 have green eyes, 100 have blue eyes. The only thing these people can do, is look each other in the eyes. There is no other form of communication. Therefore, they have no way to know what the colour of their own eyes is.
Every night, a boat comes to the island. If you can tell the captain with certainty what colour eyes you have, you can leave the island.
On day 1, a message is given to all inhabitants on the island: "There is at least one person that has green eyes."
The question is: Who can leave the island, and after how long?
Important notes:
- They are all perfect logicians
- Everyone knows the eyecolour of every OTHER inhabitant at all times. The only thing they don't know, is their own eyecolour.
- This can be solved with pure logic, not by coming up with workarounds like reflection in the water or communication with the captain.
- The only possible eyecolours are green and blue.
Everyone can leave on day one.
+ Show Spoiler +They just have to stand in a line facing one direction. The last guy of the line comes to the front and walks along the line untill he sees two persons with different eyecolors standing next to eachother, in which case he steps between them. They have to repeat this till the one who was first is at the end of the line again. He and the one after him have to go a second time. This will seperate the first group of eycolors from the rest. This group can leave.
This process can be repeated untill someone walks along the whole line whithout stepping between two persons. If this is the case he either has the same eyecolor as everyone in his group or is the only one with a different one and will never know.
If this counts as communicating then I dont know.
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On April 19 2012 05:18 DarkPlasmaBall wrote:Show nested quote +On April 19 2012 05:14 Go1den wrote:
Actually, all of the correct answers have been given so far, just not all in the same posts. See spoilers above if you want some hints/answers. Show nested quote +On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25? + Show Spoiler +1. The word "ton"
2. It's daytime
3. None (it's a hole)
4. It's an anagram
5. Only once (then it's 22) Had these but didn't want to copy everyone else -____-
25 - 5 = 22?
You still get the point though, so it's not like it matters.
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On April 19 2012 05:36 Shraft wrote:Show nested quote +On April 19 2012 05:18 DarkPlasmaBall wrote:On April 19 2012 05:14 Go1den wrote:
Actually, all of the correct answers have been given so far, just not all in the same posts. See spoilers above if you want some hints/answers. On April 19 2012 04:10 Go1den wrote:
Here are a few, they aren't too hard:
1. Forwards I'm heavy, backwards I'm not. What am I?
2. A black dog is standing in the middle of an intersection in a town painted black. A storm has caused a power outage, meaning all of the town lights are not functioning properly. A car with two broken headlights drives towards the dog, but turns in time to avoid hitting him. How could the driver have seen the dog in time?
3. How much dirt is in a hole 3 feet wide, 3 feet long, and 3 feet deep?
4. How can you rearrange the letters in "new door" to make one word?
5. How many times can you subtract the number 5 from the number 25? + Show Spoiler +1. The word "ton"
2. It's daytime
3. None (it's a hole)
4. It's an anagram
5. Only once (then it's 22) Had these but didn't want to copy everyone else -____- 25 - 5 = 22?
LOL Sorry thought it was -3. Let me fix it The answer still stands though ^^
+ Show Spoiler +It's still "Only once", because then the number is different.
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FREEAGLELAND26781 Posts
On April 19 2012 05:35 TheJizWiz wrote:Show nested quote +Okay, I have a really good one. Credit goes to the xkcd forums. I'll post the answer tomorrow. The solution is extremely counterintuitive.
There are 200 people on an abandoned island. 100 have green eyes, 100 have blue eyes. The only thing these people can do, is look each other in the eyes. There is no other form of communication. Therefore, they have no way to know what the colour of their own eyes is.
Every night, a boat comes to the island. If you can tell the captain with certainty what colour eyes you have, you can leave the island.
On day 1, a message is given to all inhabitants on the island: "There is at least one person that has green eyes."
The question is: Who can leave the island, and after how long?
Important notes:
- They are all perfect logicians
- Everyone knows the eyecolour of every OTHER inhabitant at all times. The only thing they don't know, is their own eyecolour.
- This can be solved with pure logic, not by coming up with workarounds like reflection in the water or communication with the captain.
- The only possible eyecolours are green and blue. Everyone can leave on day one. + Show Spoiler +They just have to stand in a line facing one direction. The last guy of the line comes to the front and walks along the line untill he sees two persons with different eyecolors standing next to eachother, in which case he steps between them. They have to repeat this till the one who was first is at the end of the line again. He and the one after him have to go a second time. This will seperate the first group of eycolors from the rest. This group can leave.
This process can be repeated untill someone walks along the whole line whithout stepping between two persons. If this is the case he either has the same eyecolor as everyone in his group or is the only one with a different one and will never know.
If this counts as communicating then I dont know.
I like this solution, but I do think it's communication. I think the people are more supposed to be in a state of isolation.
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the eyes riddle is well known and even though he slightly changed the wording and the solution is:
+ Show Spoiler +if there are N people with green eyes, then on the Nth night everyone on the island knows their eye color
i won't spoil the logic behind it though and it doesn't require any nonverbal communication between the inhabitants
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On April 19 2012 04:04 Bahamuth wrote:Show nested quote +On April 19 2012 03:58 flamewheel wrote:This was fun :3 + Show Spoiler [solution] +Each green sees:
99g 100b
Each blue sees:
100g 99b
Day 1: There is at least one person that has green eyes.
Start from base case--
1g Xb
The person with g will see only B. Thus at end of first day g will leave.
2g Xb
Each g will see 1g and Xb. Each g will think "if that person is the only g, he will leave at night."
Result: Neither person leaves. Both g will then deduce that the other person was not the only g, and since everybody else is b both g will leave at end of day 2.
3g Xb
Same story: each g will think that the other two g are the only 2 g. Following the [2g Xb] case each g will think "if the two g have left at end of day 2, then they were the only 2 g."
Result: None leave. All three g will deduce that the other two g are not the only ones, and since everybody else is b all three g will leave at end of day 3.
==
Doesn't matter how many blues there are. Inducting upon 1g, 2g, 3g... we arrive at the conclusion that all 100 green-eyed people will leave at the end of the 100th day.
Sucks to have blue eyes. Though not sure if correct. Edit: hmm I feel slightly better after reading other posts in this thread about this. Yes sir, very well done! If you came up with it yourself, very well done. One addition: + Show Spoiler +The people with blue eyes can just leave the day after the guys with green eyes do.
Here's a followup riddle (Spoils the answer, so don't look at if you haven't done the original yet):
+ Show Spoiler +Everyone knew that there was at least one green eyed person at the start, because they could see everyone else's eye color. So why does it matter that the message was given?
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On April 19 2012 05:35 TheJizWiz wrote:Show nested quote +Okay, I have a really good one. Credit goes to the xkcd forums. I'll post the answer tomorrow. The solution is extremely counterintuitive.
There are 200 people on an abandoned island. 100 have green eyes, 100 have blue eyes. The only thing these people can do, is look each other in the eyes. There is no other form of communication. Therefore, they have no way to know what the colour of their own eyes is.
Every night, a boat comes to the island. If you can tell the captain with certainty what colour eyes you have, you can leave the island.
On day 1, a message is given to all inhabitants on the island: "There is at least one person that has green eyes."
The question is: Who can leave the island, and after how long?
Important notes:
- They are all perfect logicians
- Everyone knows the eyecolour of every OTHER inhabitant at all times. The only thing they don't know, is their own eyecolour.
- This can be solved with pure logic, not by coming up with workarounds like reflection in the water or communication with the captain.
- The only possible eyecolours are green and blue. Everyone can leave on day one. + Show Spoiler +They just have to stand in a line facing one direction. The last guy of the line comes to the front and walks along the line untill he sees two persons with different eyecolors standing next to eachother, in which case he steps between them. They have to repeat this till the one who was first is at the end of the line again. He and the one after him have to go a second time. This will seperate the first group of eycolors from the rest. This group can leave.
This process can be repeated untill someone walks along the whole line whithout stepping between two persons. If this is the case he either has the same eyecolor as everyone in his group or is the only one with a different one and will never know.
If this counts as communicating then I dont know.
I'm puzzled by this 'there is at least one person that has green eyes'...aren't there 100 persons with green eyes, like stated above in the text?
On the first day, first person looks into eyes of every other and counts how many green eyes he saw. If he saw 100, he has blue eyes. If he saw 99, he has green eyes. He leaves.
Next person knows that the person who left has green eyes ("Everyone knows the eyecolour of every OTHER inhabitant at all times"). He counts green eyes, if he sees 99, he knows he has blue eyes. If he sees 98, he knows he has green eyes. He leaves.
And so on, everyone leaves on the first day.
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EPT
