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."
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."
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
I will thankyou!
In fact I think I have a flow chart to explain this to people somewhere.
If that pool ball riddle doesnt get figured out by morning, I will bring it to class and fiddle with it.
since tossrock and I separately came to believe that you can't do it in fewer than four weighings, and since toss said he could probably prove it, I'm tempted to think we're really right. there could be something really weird going on which makes it doable in three and that I'm just completely missing, but I swear I did think about that riddle off and on for several days without getting any farther than toss got in this thread.
It's possible to do it in three.
I don't know how but it is impossible.
I suspect it is because we are looking at this incorrectly.
We are looking at this as the scales are unbalanced.
We need to look at this as the scales go up and down and switch balls around.
I haven't figured out how to do it.
But I am sure that is the process.
Also another clue would be that after the first weighing you would have balls that you KNOW weigh the same.
im throwing in my money on it being undoable in less than 4 either.
Unless there is some stupid trick you simply can't be sure in 3
I think to solve the River City riddle you first need to have a control group. If you split the balls into three groups of four and you compare two groups you have two possible outcomes. 1: They balance, which means you have 8 balanced balls and four unknowns (the balanced would be the control group) or 2: They do not balance, which means you have a group of 4 which could be high, 4 which could be low and 4 that are the balanced or control group.
I'm not sure where to go from there, but I do know that from that point there are two possible outcomes and so you must account for both of them.
I guess that algorithms class was good for something after all, eh?
Okay, now if you take the first group (8 balanced and 4 unknown) and compare 2 unknowns to 1 unknown and 1 balanced then there are 3 outcomes. 1: They balance, 2: The 2 unknowns are lighter, and 3: the unknown and the balanced are lighter
If you have the first outcome then take the last unknown that is left and compare it to a balanced one. Once again there are 3 outcomes. 1: They balance, which means all balls are the same. 2: The unknown is heavier, which means that you have found the odd ball and it is heavier than the rest. 3: The unknown is lighter, which means that you have found the odd ball and it is lighter than the rest.
I'm done for the night, feel free to play with the rest of this.
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
I will thankyou!
In fact I think I have a flow chart to explain this to people somewhere.
theres a big wikipedia page on it
i forget what its called
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Kovakdid a lot of drugsmarried cher?Registered Userregular
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
is this something silly like the host is lying?
when you fist chose
you had a 1/3 chance of picking the correct one
now with one door open
you have a 1/2 chance of picking the right one by switching
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
I will thankyou!
In fact I think I have a flow chart to explain this to people somewhere.
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
is this something silly like the host is lying?
when you fist chose
you had a 1/3 chance of picking the correct one
now with one door open
you have a 1/2 chance of picking the right one by switching
odds are better if you switch
you have failed to correctly explain why you should switch
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VivixenneRemember your training, and we'll get through this just fine.Registered Userregular
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
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 also like this one. it's basically the perfect difficulty, I think
I guess if we're listing our favorites I can tell the riddle I alluded to earlier. I forget the setup to it so I'm just going to make one up.
Fifty soldiers are captured by the enemy. They're taken to a room where they are all told what's going to happen to them next, which is this: after being given time to plan, they will be led to another room, at which point they will not be allowed to speak or communicate in any way. They will be lined up single file all facing the same direction, and then they will have hats placed on their heads. The hats will be either black or white, and no solider will be able to see the color of his own hat, although he can see the hats of all the people in front of him. Then, going from the back of the line to the front (that means starting with the guy who can see everyone's hat but his own), they will be asked "What color is your hat?" to which they can answer either "Black" or "White." Anyone who misidentifies their hat color is doomed to die.
Remember, they can plan out their strategy beforehand while they are still allowed to talk (but before they see the hats). There's a way they can plan it out so that no more than one of them even has a chance at death. How?
Note: The answer doesn't involve any tricks. They don't get around the "no communication" rule by poking or gesturing or changing their tone of voice as they answer black or white or any of that other jazz. You can solve this without needing any bullshit.
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Blake TDo you have enemies then?Good. That means you’ve stood up for something, sometime in your life.Registered Userregular
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
I will thankyou!
In fact I think I have a flow chart to explain this to people somewhere.
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
I will thankyou!
In fact I think I have a flow chart to explain this to people somewhere.
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
is this something silly like the host is lying?
when you fist chose
you had a 1/3 chance of picking the correct one
now with one door open
you have a 1/2 chance of picking the right one by switching
odds are better if you switch
you have failed to correctly explain why you should switch
check yo maths
this is the monty hall problme
Because there is no way for the player to know which of the two unopened doors is the winning door, most people assume that each door has an equal probability and conclude that switching does not matter. In fact, in the usual interpretation of the problem the player should switch—doing so doubles the probability of winning the car from 1/3 to 2/3. Switching is only not advantageous if the player initially chooses the winning door, which happens with probability 1/3. With probability 2/3, the player initially chooses one of two losing doors; when the other losing door is revealed, switching yields the winning door with certainty. The total probability of winning when switching is thus 2/3.
it's the same thing
as saying you have a 1/3 chance
and then a 1/2 chance of picking
i just recalculated odds with 2 doors instead of sticking with the same total number of choices
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
I will thankyou!
In fact I think I have a flow chart to explain this to people somewhere.
I will add that often people ask this riddle while leaving out the crucial detail that the host knows what's behind each door. If the host doesn't know, you don't better your odds by switching.
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VivixenneRemember your training, and we'll get through this just fine.Registered Userregular
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
I will thankyou!
In fact I think I have a flow chart to explain this to people somewhere.
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 also like this one. it's basically the perfect difficulty, I think
I guess if we're listing our favorites I can tell the riddle I alluded to earlier. I forget the setup to it so I'm just going to make one up.
Fifty soldiers are captured by the enemy. They're taken to a room where they are all told what's going to happen to them next, which is this: after being given time to plan, they will be led to another room, at which point they will not be allowed to speak or communicate in any way. They will be lined up single file all facing the same direction, and then they will have hats placed on their heads. The hats will be either black or white, and no solider will be able to see the color of his own hat, although he can see the hats of all the people in front of him. Then, going from the back of the line to the front (that means starting with the guy who can see everyone's hat but his own), they will be asked "What color is your hat?" to which they can answer either "Black" or "White." Anyone who misidentifies their hat color is doomed to die.
Remember, they can plan out their strategy beforehand while they are still allowed to talk (but before they see the hats). There's a way they can plan it out so that no more than one of them even has a chance at death. How?
Note: The answer doesn't involve any tricks. They don't get around the "no communication" rule by poking or gesturing or changing their tone of voice as they answer black or white or any of that other jazz. You can solve this without needing any bullshit.
this seems too easy
the first guy just says the number of white hats he sees modulo 2
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
is this something silly like the host is lying?
when you fist chose
you had a 1/3 chance of picking the correct one
now with one door open
you have a 1/2 chance of picking the right one by switching
odds are better if you switch
you have failed to correctly explain why you should switch
check yo maths
this is the monty hall problme
Because there is no way for the player to know which of the two unopened doors is the winning door, most people assume that each door has an equal probability and conclude that switching does not matter. In fact, in the usual interpretation of the problem the player should switch—doing so doubles the probability of winning the car from 1/3 to 2/3. Switching is only not advantageous if the player initially chooses the winning door, which happens with probability 1/3. With probability 2/3, the player initially chooses one of two losing doors; when the other losing door is revealed, switching yields the winning door with certainty. The total probability of winning when switching is thus 2/3.
it's the same thing
as saying you have a 1/3 chance
and then a 1/2 chance of picking
i just recalculated odds with 2 doors instead of sticking with the same total number of choices
good job looking to wikipedia for your answer fag
and still getting it wrong
it is NOT 50% by switching and it even says so in the text you quoted fool
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Kovakdid a lot of drugsmarried cher?Registered Userregular
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
I will thankyou!
In fact I think I have a flow chart to explain this to people somewhere.
In order not to be the second-lowest bidder (who would lose his money with no returns) each bidder will continue to bid higher and higher. Once the bidding reaches $100 it would continue to go infinitely higher since it's better to pay $101 for a $100 bill than lose $99 outright.
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
is this something silly like the host is lying?
when you fist chose
you had a 1/3 chance of picking the correct one
now with one door open
you have a 1/2 chance of picking the right one by switching
odds are better if you switch
you have failed to correctly explain why you should switch
check yo maths
this is the monty hall problme
Because there is no way for the player to know which of the two unopened doors is the winning door, most people assume that each door has an equal probability and conclude that switching does not matter. In fact, in the usual interpretation of the problem the player should switch—doing so doubles the probability of winning the car from 1/3 to 2/3. Switching is only not advantageous if the player initially chooses the winning door, which happens with probability 1/3. With probability 2/3, the player initially chooses one of two losing doors; when the other losing door is revealed, switching yields the winning door with certainty. The total probability of winning when switching is thus 2/3.
it's the same thing
as saying you have a 1/3 chance
and then a 1/2 chance of picking
i just recalculated odds with 2 doors instead of sticking with the same total number of choices
good job looking to wikipedia for your answer fag
and still getting it wrong
it is NOT 50% by switching and it even says so in the text you quoted fool
the last part was my math
and once again
i am aware of how the stupid trick to that riddle works
i simply forgot the exact fractions of chance.
Since i maintained your first door had a 1/3 chance of being correct and the switch had a 50% chance although it actually has a 2/3 chance
Posts
Split each pair of socks and give one of each to the two.
#5 and #10 go across, #2 returns (3 + 12 = 15 minutes)
#2 and #1 go across (2 + 15 = 17 minutes)
Randall this question is retarded.
You say everyone on this island is logical.
Then you say the Guru is a woman
Stop being dumb.
Satans..... hints.....
You're on a game show and you have a chance to win a new car by choosing from one of three doors. Only one of them has a car behind it and the other two just have a bicycle, and the host knows which door the car is behind. You select door number one, and the host then reveals that behind door number three is a bicycle and asks if you want to change your choice.
Do you?
Repeat.
In fact I think I have a flow chart to explain this to people somewhere.
Satans..... hints.....
im throwing in my money on it being undoable in less than 4 either.
Unless there is some stupid trick you simply can't be sure in 3
the closet i can get is a 50 50 chance between 2
Okay, now if you take the first group (8 balanced and 4 unknown) and compare 2 unknowns to 1 unknown and 1 balanced then there are 3 outcomes. 1: They balance, 2: The 2 unknowns are lighter, and 3: the unknown and the balanced are lighter
If you have the first outcome then take the last unknown that is left and compare it to a balanced one. Once again there are 3 outcomes. 1: They balance, which means all balls are the same. 2: The unknown is heavier, which means that you have found the odd ball and it is heavier than the rest. 3: The unknown is lighter, which means that you have found the odd ball and it is lighter than the rest.
I'm done for the night, feel free to play with the rest of this.
now i am off to uni to crush what little is left of my genius level problem solving ability
is this something silly like the host is lying?
theres a big wikipedia page on it
i forget what its called
when you fist chose
you had a 1/3 chance of picking the correct one
now with one door open
you have a 1/2 chance of picking the right one by switching
odds are better if you switch
in spoilers
I like this one, too.
I also like this one. it's basically the perfect difficulty, I think
I guess if we're listing our favorites I can tell the riddle I alluded to earlier. I forget the setup to it so I'm just going to make one up.
Fifty soldiers are captured by the enemy. They're taken to a room where they are all told what's going to happen to them next, which is this: after being given time to plan, they will be led to another room, at which point they will not be allowed to speak or communicate in any way. They will be lined up single file all facing the same direction, and then they will have hats placed on their heads. The hats will be either black or white, and no solider will be able to see the color of his own hat, although he can see the hats of all the people in front of him. Then, going from the back of the line to the front (that means starting with the guy who can see everyone's hat but his own), they will be asked "What color is your hat?" to which they can answer either "Black" or "White." Anyone who misidentifies their hat color is doomed to die.
Remember, they can plan out their strategy beforehand while they are still allowed to talk (but before they see the hats). There's a way they can plan it out so that no more than one of them even has a chance at death. How?
Note: The answer doesn't involve any tricks. They don't get around the "no communication" rule by poking or gesturing or changing their tone of voice as they answer black or white or any of that other jazz. You can solve this without needing any bullshit.
hangon
I'm coding it up.
Satans..... hints.....
check yo maths
Because there is no way for the player to know which of the two unopened doors is the winning door, most people assume that each door has an equal probability and conclude that switching does not matter. In fact, in the usual interpretation of the problem the player should switch—doing so doubles the probability of winning the car from 1/3 to 2/3. Switching is only not advantageous if the player initially chooses the winning door, which happens with probability 1/3. With probability 2/3, the player initially chooses one of two losing doors; when the other losing door is revealed, switching yields the winning door with certainty. The total probability of winning when switching is thus 2/3.
it's the same thing
as saying you have a 1/3 chance
and then a 1/2 chance of picking
i just recalculated odds with 2 doors instead of sticking with the same total number of choices
here it is
http://en.wikipedia.org/wiki/Two_envelopes_problem
hey!
this seems too easy
the first guy just says the number of white hats he sees modulo 2
and still getting it wrong
it is NOT 50% by switching and it even says so in the text you quoted fool
its a mathematical thing and no one is gonna explain it well
and people have started trying anyway so what
would you promise to be true
Tumblr blargh
so everything works out well
except that is the answer to the first problem I posted, you faggot
the last part was my math
and once again
i am aware of how the stupid trick to that riddle works
i simply forgot the exact fractions of chance.
Since i maintained your first door had a 1/3 chance of being correct and the switch had a 50% chance although it actually has a 2/3 chance
wrong.