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Riddle Me This!
Vixx
Valkyrie: prepared!Registered User regular
Valkyrie: prepared!Registered User regular
CALLING ALL MENSA-LEVEL GLOSSIES!
I have recently been on a riddle-solving kick and I ran a search for some keywords in these riddles and have not found any previous instance of them on the forums, even though they've been around a while.
I DO NOT KNOW THE ANSWER TO ALL OF THEM and it is driving me crazy so I am enlisting your help.
***I am putting all the solved puzzles into one big spoiler so that the OP is easier to look at. Do check them out if you want a challenge though!
SOLVED AND CONFIRMED
SOLVED BUT NEEDING RECONFIRMATION
ENLIGHTENMENT - previous solution by garroad_ran is incorrect
SAILOR'S DELIGHT - unsolved
THREE GODS - unsolved
ICE, ICE BABY - unsolved
They are obviously coming from a source website, but I'll try to find more when I get round to trying to solve more of them. As it is I've only made it up to River City in terms of attempting to solve the riddles.
PLEASE PUT THE NAME OF THE RIDDLE YOU ARE DISCUSSING AT THE TOP OF YOUR POST SOMEWHERE so that we know what you're talking about. I'm throwing bunches of them up at once just cuz people tend to be better at one type of riddles than others.
Finally, forumer-recommended riddles go below. I'm no pro at riddles, but I know good ones when I see them, and I will put ones that I think are good in here.
Randall_Flagg's Eye Problem - riddle source solution revealed
Druhim's Wheel of Misfortune - solved! - by everyone who's ever heard of the Monty Hall Problem
Redhead's Soldier Hats - solved! - kinda-sorta by Randall_Flagg, explained by Framling
I have recently been on a riddle-solving kick and I ran a search for some keywords in these riddles and have not found any previous instance of them on the forums, even though they've been around a while.
I DO NOT KNOW THE ANSWER TO ALL OF THEM and it is driving me crazy so I am enlisting your help.
***I am putting all the solved puzzles into one big spoiler so that the OP is easier to look at. Do check them out if you want a challenge though!
SOLVED AND CONFIRMED
Three Dots - solved! - by garroad_ran
Three's a Crowd - solved! - by Pony
Lying Defeeted - solved! - by Druhim
Open Door Policy - solved! - by Fiz
Light Bridge - solved! - by garroad_ran
Apairantly Not - solved! - by No Great Name
Tractor Beam - solved! - by trentsteel
Auction Action - solved! - by garroad_ran
No Vacancies Parts I and II - solved! - Part I by garroad_ran and Part II by a trite and unhelpful Randall_Flagg
Ties That Bind - solved! - by garroad_ran
Hat-Trick - solved! - by Randall_Flagg
Beads, Boxes, and a Blindfold - solved! - by Narbus and Fishman
Rosencrantz and Guildenstern Redux - solved! - by Hirocon
Coin in a Bottle - solved! - by stimkolos
You are travelling in a deep, dark forest when, suddenly, on a dark and stormy night, you are captured by the kind-but-not-so-bright forest people. They keep looking at you and saying to each other, "It be a smart person!"
You are marched to their village and seated in the square. Before you are blindfolded, you notice two other lucky souls seated in chairs facing you. Then you are told that the forest people king is about to die. He previously sent messengers throughout the land seeking the 3 smartest people. You are one, and two others have also been found. He now gives you all a task to see which one is the wisest.
He tells you, "I have seated you in an equilateral triangle so that each of you faces the other two. While you are blindfolded I will paint a dot on each of your foreheads. Each dot will be red or green so that there can be any combination of red and green dots, for example, 1 red and 2 greens, or all red, etc. When I remove the blindfolds each of you must raise your hand if you see _any_ green dots, i.e. 1 or 2 dots. As soon as you have figured out what color your own dot is, tell me how you knew."
So he paints a green dot on all three foreheads. When the blindfolds are removed, all three hands go up. After a long pause, the wisest person, (that's you!) say, "Your highness, I have a green dot. The reason I know this is that..."
How did you know?
You are marched to their village and seated in the square. Before you are blindfolded, you notice two other lucky souls seated in chairs facing you. Then you are told that the forest people king is about to die. He previously sent messengers throughout the land seeking the 3 smartest people. You are one, and two others have also been found. He now gives you all a task to see which one is the wisest.
He tells you, "I have seated you in an equilateral triangle so that each of you faces the other two. While you are blindfolded I will paint a dot on each of your foreheads. Each dot will be red or green so that there can be any combination of red and green dots, for example, 1 red and 2 greens, or all red, etc. When I remove the blindfolds each of you must raise your hand if you see _any_ green dots, i.e. 1 or 2 dots. As soon as you have figured out what color your own dot is, tell me how you knew."
So he paints a green dot on all three foreheads. When the blindfolds are removed, all three hands go up. After a long pause, the wisest person, (that's you!) say, "Your highness, I have a green dot. The reason I know this is that..."
How did you know?
Three's a Crowd - solved! - by Pony
After solving the riddle of the three wise folks, three scoundrels claim to be the smartest in the country. So you decide to give them a challenge. Suspecting that the thing they care about most is money, you give them $100 and tell them they are to divide this money observing the following rule: they are to discuss offers and counter-offers from each other and then take a vote. Majority vote wins.
Sounds easy enough... now the question is, assuming each person is motivated to take the largest amount possible, what will the outcome be?
Note: careful... if the answer were that they split it 50% / 50% / 0%, or 1/3 / 1/3 / 1/3, it wouldn't be a riddle!
Note: careful... 96.6523544 % of people who send answers to this have not thought about it for even 1 minute. I guarantee you won't solve it in a minute. (96.6523544% of the time this guarantee is correct.)
Sounds easy enough... now the question is, assuming each person is motivated to take the largest amount possible, what will the outcome be?
Note: careful... if the answer were that they split it 50% / 50% / 0%, or 1/3 / 1/3 / 1/3, it wouldn't be a riddle!
Note: careful... 96.6523544 % of people who send answers to this have not thought about it for even 1 minute. I guarantee you won't solve it in a minute. (96.6523544% of the time this guarantee is correct.)
Lying Defeeted - solved! - by Druhim
After being the ruler of the forest people for a while, you get bored. So you visit an island on which two tribes of natives live. One tribe has purple soles and always lies; the other tribe has green soles and always tells the truth. There are three natives standing near you. You can't see the bottoms of their feet, and indeed you find out it is rude to look at another's soles, but you are curious so you ask the first man,
"Sir, what color are your soles?" Now he happens to understand English, but he can't speak it, so he replies in his native tongue, "Glub Glub". Though you don't speak the language, you know that "Glub Glub" either means purple or green.
You turn to the second man and ask, "Sir, what did he say?" The second man replies, "He said he has green soles."
Now to be sure, you turn to the third and ask, "Sir, what color of soles does this second man have?" The third man replies, "Sir, he has purple soles."
Now the question is, what color of soles does the third native have?
"Sir, what color are your soles?" Now he happens to understand English, but he can't speak it, so he replies in his native tongue, "Glub Glub". Though you don't speak the language, you know that "Glub Glub" either means purple or green.
You turn to the second man and ask, "Sir, what did he say?" The second man replies, "He said he has green soles."
Now to be sure, you turn to the third and ask, "Sir, what color of soles does this second man have?" The third man replies, "Sir, he has purple soles."
Now the question is, what color of soles does the third native have?
Open Door Policy - solved! - by Fiz
On your trip back from the Island people to the deep dark forest, you get lost. A trap door suddenly opens and you fall down into a dark chamber.
You hear a voice, "You are trespassing and the penalty is death. In five minutes you will be buried alive. However due to our exceeding kindness and mercy, and because you were once ruler of the forest people, we will allow you to earn your life back. In this dark chamber there are two doors. You may choose to open either one - if you choose correctly, you will go free. If you choose incorrectly, well, instead of just being buried alive, you will be eaten alive by army ants.
To help you choose a door, you may ask a question. However, you should know that two people will hear you and one of them always lies and the other one always tells the truth. One of them will answer your question, but you will not know which one. Each of them knows which door leads to freedom.
Good Luck, you have four and a half minutes left."
What question do you ask to win your freedom? (At least two solutions.)
You hear a voice, "You are trespassing and the penalty is death. In five minutes you will be buried alive. However due to our exceeding kindness and mercy, and because you were once ruler of the forest people, we will allow you to earn your life back. In this dark chamber there are two doors. You may choose to open either one - if you choose correctly, you will go free. If you choose incorrectly, well, instead of just being buried alive, you will be eaten alive by army ants.
To help you choose a door, you may ask a question. However, you should know that two people will hear you and one of them always lies and the other one always tells the truth. One of them will answer your question, but you will not know which one. Each of them knows which door leads to freedom.
Good Luck, you have four and a half minutes left."
What question do you ask to win your freedom? (At least two solutions.)
Light Bridge - solved! - by garroad_ran
You decide to go home. Unfortunately you must take an old, old bridge across a deep, dark chasm. It is dark and there are so many steps missing that you ask to borrow a flashlight. Three forest people approach and offer you a flashlight in return for helping them across the bridge. Now the bridge allows a maximum of 2 people at once and for safety, there must always be someone on the bridge holding a flashlight (of which there is only 1). In addition, the three forest people take 2, 5, and 10 minutes respectively to cross the bridge. You, being highly motivated, need only 1 minute.
No problem, you think, we'll just take turns walking folks back and forth with the light until we're all across. But the bridge is enchanted and every million years, it vanishes for a century and that will happen in exactly 17 minutes.
How will all four of you make it to the other side of the bridge in 17 minutes?
(Note: Call these people #1 #2 #5 and #10. If you and #10 go across and you return, that takes 11 minutes. Then you and #5 could go across and you return; we are now up to 17 minutes... *poof* - bridge is gone.
The light carrier doesn't have to be you. If the light carrier is accompanied by anyone, they must stay together the whole way across - you cannot have one person stand in the middle and shine the light. No piggy-backs, no simultaneous-2-way-crossings, etc.)
No problem, you think, we'll just take turns walking folks back and forth with the light until we're all across. But the bridge is enchanted and every million years, it vanishes for a century and that will happen in exactly 17 minutes.
How will all four of you make it to the other side of the bridge in 17 minutes?
(Note: Call these people #1 #2 #5 and #10. If you and #10 go across and you return, that takes 11 minutes. Then you and #5 could go across and you return; we are now up to 17 minutes... *poof* - bridge is gone.
The light carrier doesn't have to be you. If the light carrier is accompanied by anyone, they must stay together the whole way across - you cannot have one person stand in the middle and shine the light. No piggy-backs, no simultaneous-2-way-crossings, etc.)
Apairantly Not - solved! - by No Great Name
After barely making it across the bridge, you hear two of the forest people arguing. It seems that just before they crossed the bridge, they each bought 10 pair of socks, and in fact, as far as color and size go, they each bought the same exact 10 pairs. Each person has 1 pair of green, 1 pair of blue, etc. etc... But now they have accidentally dropped all their socks and the socks are all mixed up in a pile on the ground.
Because it is pitch-black, they can't see what colors the socks are, but want to divide them up so that they each have the same colors that they bought, i.e. identical sets of green, blue, etc. Luckily the socks are all still in pairs, so they only have to pick up 20 pairs, not 40 individual socks.
The light used in crossing the bridge fell into a bottomless forest pit, so even though it is pitch-black, how can you help the two forest people get one pair each of every color, just like they had before they dropped them?
(Note: no lights, moon, cigarette lighter, etc...)
Because it is pitch-black, they can't see what colors the socks are, but want to divide them up so that they each have the same colors that they bought, i.e. identical sets of green, blue, etc. Luckily the socks are all still in pairs, so they only have to pick up 20 pairs, not 40 individual socks.
The light used in crossing the bridge fell into a bottomless forest pit, so even though it is pitch-black, how can you help the two forest people get one pair each of every color, just like they had before they dropped them?
(Note: no lights, moon, cigarette lighter, etc...)
Tractor Beam - solved! - by trentsteel
You watch the sock-hoppers amble off toward a pier and notice a small island about a mile away from shore. Due to your excellent forest vision, you see a Forest person plowing a field with a large tractor. There are no bridges or tunnels to the island and you wonder how the tractor got out to the island.
"That's a good question," says a nearby forest person, reading your mind. "I have the only boat around here and it's not big enough to carry that tractor over. I didn't drop off any parts either so he couldn't have built it there. No one has an airplane or helicopter to drop it off either."
So how did the tractor get on the island?
(Notes:
1. the tractor was not built on the island
2. even with tides, the water is too deep to drive across
3. it was not driven across the bottom of the ocean or under water
4. it was not disassembled)
"That's a good question," says a nearby forest person, reading your mind. "I have the only boat around here and it's not big enough to carry that tractor over. I didn't drop off any parts either so he couldn't have built it there. No one has an airplane or helicopter to drop it off either."
So how did the tractor get on the island?
(Notes:
1. the tractor was not built on the island
2. even with tides, the water is too deep to drive across
3. it was not driven across the bottom of the ocean or under water
4. it was not disassembled)
Auction Action - solved! - by garroad_ran
After using the same method that the tractor took to get to the Island, you drop in on a party of the forest people and notice Prof. Chaos with an evil look in her eye. Folks look bored, so she decides to engage in a little mischief. "I will give this $100 bill to the highest bidder. The only rule is that the person who bids the second highest amount will also have to pay me that bid. The highest bidder pays the high bid and takes the bill, even if the highest bid is only 5 cents."
People start to murmur. Then you hear "A nickel!". "A Dime!". "Two Dollars!"...
Question: what is Prof. Chaos up to?
People start to murmur. Then you hear "A nickel!". "A Dime!". "Two Dollars!"...
Question: what is Prof. Chaos up to?
No Vacancies Parts I and II - solved! - Part I by garroad_ran and Part II by a trite and unhelpful Randall_Flagg
PART I ---
In the forest, a hotel has an infinite number of rooms. An infinite number of forest people arrive and each takes a room. So far so good. Now you would like a room.
Can the hotel accomodate you? If so, how?
(Please enjoy this riddle instead of writing that infinity is the same as infinity plus 1 or some such gibberish! However, you must find _rooms_ for everybody, no doubling up, sleeping in the kitchen etc.)
PART II ---
The hotel has an infinite number of rooms. An infinite number of forest people arrive and each takes a room. So far so good. Now another infinite number of guests arrive.
Can the hotel accomodate them all? If so, how?
(see the note above on "No Vacancy")
In the forest, a hotel has an infinite number of rooms. An infinite number of forest people arrive and each takes a room. So far so good. Now you would like a room.
Can the hotel accomodate you? If so, how?
(Please enjoy this riddle instead of writing that infinity is the same as infinity plus 1 or some such gibberish! However, you must find _rooms_ for everybody, no doubling up, sleeping in the kitchen etc.)
PART II ---
The hotel has an infinite number of rooms. An infinite number of forest people arrive and each takes a room. So far so good. Now another infinite number of guests arrive.
Can the hotel accomodate them all? If so, how?
(see the note above on "No Vacancy")
Ties That Bind - solved! - by garroad_ran
You have 2 long strings which burn at random rates at different positions on their length. Though they are not identical, they do burn exactly 1 hour each. A string might burn 99% of it's length in 1 minute, then take 59 minutes to burn the rest of the way.
You have no way of telling time; clock, watch, sunset, etc. but need to measure 45 minutes.
Using these string and a lighter, how can you measure 45 minutes?
You have no way of telling time; clock, watch, sunset, etc. but need to measure 45 minutes.
Using these string and a lighter, how can you measure 45 minutes?
Hat-Trick - solved! - by Randall_Flagg
There are two people sitting behind you, so there are three people facing the same direction. The other two are the two smartest people in the forest (a scary thought). There are five hats: three are red and two are purple.
While all of your eyes are closed, a hat is placed on each person's head and the two unused hats are hidden. Then all are allowed to look only forward so that each of you can only see the people in front of you (the person in the back can see the hats of the two people in front; the middle person can see your hat; you can't see any hats at all; so you might as well keep your eyes closed!)
When someone figures out what color hat they are wearing, they must call out. No one has called out yet. What color hat are you wearing and how do you know?
While all of your eyes are closed, a hat is placed on each person's head and the two unused hats are hidden. Then all are allowed to look only forward so that each of you can only see the people in front of you (the person in the back can see the hats of the two people in front; the middle person can see your hat; you can't see any hats at all; so you might as well keep your eyes closed!)
When someone figures out what color hat they are wearing, they must call out. No one has called out yet. What color hat are you wearing and how do you know?
Beads, Boxes, and a Blindfold - solved! - by Narbus and Fishman
First puzzle from another site!
You have been named as a traitor by the King, the punishment for this crime is death. Although he is a cruel tyrant he gives you one last chance at freedom. When you are finally brought before him he has this to say to you:
"There are 100 beads, 50 black and 50 white. You will be allowed to draw one bead, whilst blindfolded of course. If it is black you will be condemned to death, if it is white you will be set free".
So far so good you think to yourself, at least I have a 50/50 chance.
"The beads will be distributed amongst four boxes by me," he continued. "You must select a box by opening it, draw one bead from it and then present the bead to the court. Thus will your fate be decided".
Upon saying this a cruel smile appears on the King's face and you suddenly break into a cold sweat as you remember that the King is both very wicked and devilishly cunning.
Assuming that the King is incredibly smart, evil, thinks that you are a stupid, uneducated peasant and wants to minimise your chance of freedom, what strategy should you employ, and what is the probability of surviving?
You have been named as a traitor by the King, the punishment for this crime is death. Although he is a cruel tyrant he gives you one last chance at freedom. When you are finally brought before him he has this to say to you:
"There are 100 beads, 50 black and 50 white. You will be allowed to draw one bead, whilst blindfolded of course. If it is black you will be condemned to death, if it is white you will be set free".
So far so good you think to yourself, at least I have a 50/50 chance.
"The beads will be distributed amongst four boxes by me," he continued. "You must select a box by opening it, draw one bead from it and then present the bead to the court. Thus will your fate be decided".
Upon saying this a cruel smile appears on the King's face and you suddenly break into a cold sweat as you remember that the King is both very wicked and devilishly cunning.
Assuming that the King is incredibly smart, evil, thinks that you are a stupid, uneducated peasant and wants to minimise your chance of freedom, what strategy should you employ, and what is the probability of surviving?
Rosencrantz and Guildenstern Redux - solved! - by Hirocon
You notice a line of quarters right there on the ground. The line goes on and on, clear into the forest. "There must be thousands of them!" you exclaim.
"Infinite, to be exact." says the voice of an evil forest person. "And you can have them all if you divide them into two piles which have the same number of heads."
"How much time do I have?"
"1 day. You can pick up as many quarters as you want and even flip them over, just as long as you wind up with two piles that have the same number of heads. I happen to know that there are 20 heads, the rest are all tails."
"Do the piles need to have the same total number of quarters?" you ask observantly.
"No, just the same number of heads. If you're ready to begin, here's the blindfold."
"What blindfold?"
"The one you have to wear while solving this riddle!"
Question: Given infinte coins,
* only 20 of which are heads, and
* wearing a blindfold,
* flipping however many you want ...
how can you divide the coins into two piles, each with the same number of heads?
Notes:
* You can pick up, flip, etc. as many coins as you want.
* You can't remove any coins.
* You must make 2 piles of coins.
* No peeking allowed.
* It's not a probababalistical problem.
"Infinite, to be exact." says the voice of an evil forest person. "And you can have them all if you divide them into two piles which have the same number of heads."
"How much time do I have?"
"1 day. You can pick up as many quarters as you want and even flip them over, just as long as you wind up with two piles that have the same number of heads. I happen to know that there are 20 heads, the rest are all tails."
"Do the piles need to have the same total number of quarters?" you ask observantly.
"No, just the same number of heads. If you're ready to begin, here's the blindfold."
"What blindfold?"
"The one you have to wear while solving this riddle!"
Question: Given infinte coins,
* only 20 of which are heads, and
* wearing a blindfold,
* flipping however many you want ...
how can you divide the coins into two piles, each with the same number of heads?
Notes:
* You can pick up, flip, etc. as many coins as you want.
* You can't remove any coins.
* You must make 2 piles of coins.
* No peeking allowed.
* It's not a probababalistical problem.
Coin in a Bottle - solved! - by stimkolos
If you put a coin in an empty bottle and insert a cork into the neck of the bottle, how could you remove the coin without taking the cork out or breaking the bottle?
SOLVED BUT NEEDING RECONFIRMATION
Trouble in River City - solved! - by Marshmallow - needs triple-checking!
Susan, She is So Lazy - solved! - by Hirocon - needs triple-checking!
After asking which door he would send his Mother-In-Law through and choosing the other one (Open Door Policy), you are allowed to walk through the Door of Freedom. After taking a few deep breaths of fresh air, you set out to escape this deep dark forest. As fate would have it, you feel a thud on your noggin and wake up in a dimly lit room with a pool table. You are about to be challenged to a game of 9-ball when the wicked forest people notice chalk on your hand. Wary of the possibility of you turning out to be a pool shark, they give you this challenge instead.
On the pool table are 12 balls of identical size. And all are of identical weight except possibly one, which is either slightly heavier or slightly lighter than all the others, but not enough for you to be able to tell just by holding it. So you don't know whether they all weigh the same, or whether there is one odd one. And if there is an odd one, you don't know whether it's light or heavy.
Now the evil forest people bring a balance scale so that you may compare objects against each other. "No problem" you're thinking. "I'll just compare them to each other to find the exception." However, you are then informed that you may only use the scale three times.
How do you use the balance scales so that in just three comparisons, you determine they all weight the same, or find the one suspicious ball and know whether it is heavier or lighter?
Hints:
* If you think you are looking for a heavier ball, please re-read the riddle.
* If you think you are looking for a lighter ball, and have read the previous hint, immediately box up your computer and ship it back to the manufacturer, because you are too stupid to own a computer.
On the pool table are 12 balls of identical size. And all are of identical weight except possibly one, which is either slightly heavier or slightly lighter than all the others, but not enough for you to be able to tell just by holding it. So you don't know whether they all weigh the same, or whether there is one odd one. And if there is an odd one, you don't know whether it's light or heavy.
Now the evil forest people bring a balance scale so that you may compare objects against each other. "No problem" you're thinking. "I'll just compare them to each other to find the exception." However, you are then informed that you may only use the scale three times.
How do you use the balance scales so that in just three comparisons, you determine they all weight the same, or find the one suspicious ball and know whether it is heavier or lighter?
Hints:
* If you think you are looking for a heavier ball, please re-read the riddle.
* If you think you are looking for a lighter ball, and have read the previous hint, immediately box up your computer and ship it back to the manufacturer, because you are too stupid to own a computer.
Susan, She is So Lazy - solved! - by Hirocon - needs triple-checking!
Placed in front of you is a "Lazy Susan" with four shot glasses placed equally apart around the outer edge. They have been randomly placed either right side up or upside down and it is your challenge to get them all oriented the same way; that is, either all four up, or all four down, as quickly as possible.
Of course you will be blindfolded! You're not surprised...
Each turn the Lazy Suzan will be spun and you may then touch any two glasses, and then decide to keep each as it is or turn either one, or both, over. OK?
You may keep both that you touch the same, turn them both over, or turn just one of them over (your choice, either one). Obviously, as you reach down to grab two of the glasses you will be able to tell which two of the four you are touching - both in front of you; both away from you; the two on the left; the two on the right; or either of the two corner to corners.
You will start with a $10,000 Prize Fund which will be decreased by $1,000 after each turn. I will stand next to you and announce after each of your efforts whether you have solved the puzzle. Of course, there's no chance in the whole world that you will be so lucky as to start with all four in a winning position, but of course you already knew that. And also, if you decide to rely on luck to get you to the final solution you should understand that once the $10,000 Prize fund is gone, you will then have to start paying $1,000 for each wrong guess you make from then on out - No Stopping until you get it right!
Question: What process can you use to guarantee success?
Of course you will be blindfolded! You're not surprised...
Each turn the Lazy Suzan will be spun and you may then touch any two glasses, and then decide to keep each as it is or turn either one, or both, over. OK?
You may keep both that you touch the same, turn them both over, or turn just one of them over (your choice, either one). Obviously, as you reach down to grab two of the glasses you will be able to tell which two of the four you are touching - both in front of you; both away from you; the two on the left; the two on the right; or either of the two corner to corners.
You will start with a $10,000 Prize Fund which will be decreased by $1,000 after each turn. I will stand next to you and announce after each of your efforts whether you have solved the puzzle. Of course, there's no chance in the whole world that you will be so lucky as to start with all four in a winning position, but of course you already knew that. And also, if you decide to rely on luck to get you to the final solution you should understand that once the $10,000 Prize fund is gone, you will then have to start paying $1,000 for each wrong guess you make from then on out - No Stopping until you get it right!
Question: What process can you use to guarantee success?
ENLIGHTENMENT - previous solution by garroad_ran is incorrect
Strolling through the forest, you hear a muffled shout. Investigating further, you come to a closed, solid, light-proof door. "... need Light! Light!..." you can barely make out coming through the door.
"Use the switches to know which one controls the Light!" you hear the voice say as you notice FOUR on/off switches beside the door.
Inside the cave is an incandescent lamp which is now off. Next to the door are FOUR switches. One of these four switches turns the lamp in the room on and off.
Your job is to figure out which switch controls the lamp. However, you can't just open the door and look. In fact, you can only enter the cave one time and then you have to say which switch controls the lamp. There are no windows, holes, cracks, leaks, bleeding-heart-liberals, etc. You are allowed to set any switches on or off and then enter the cave. That's it.
What will you do to know with certainty which switch controls the lamp?
"Use the switches to know which one controls the Light!" you hear the voice say as you notice FOUR on/off switches beside the door.
Inside the cave is an incandescent lamp which is now off. Next to the door are FOUR switches. One of these four switches turns the lamp in the room on and off.
Your job is to figure out which switch controls the lamp. However, you can't just open the door and look. In fact, you can only enter the cave one time and then you have to say which switch controls the lamp. There are no windows, holes, cracks, leaks, bleeding-heart-liberals, etc. You are allowed to set any switches on or off and then enter the cave. That's it.
What will you do to know with certainty which switch controls the lamp?
SAILOR'S DELIGHT - unsolved
10 pirates are ranked in order, first to last. After finding a treasure chest of 100 gold coins, they are discussing how to divide up the booty. They allow the lowest ranked sailor to divide up the coins and then vote on his idea. If the number of pirates who like the division is equal to or greater than the others who don't like it, then the boss will say, "Make it So." (The proposer of the idea also has a vote.)
Otherwise... well, being pirates their simple solution is to dump the unfortunate sailor into the deep blue sea and let the next pirate in line decide how to divide up the spoils.
Question: How many pirates will be thrown into the sea?
Notes:
* Pirates are smart, want money, and love life, especially their own.
* This one is harder than average. If you are stuck, think of fewer pirates...
* Why would #1 ever vote for any schemes?
* Why would #2 ever vote for any schemes?
Otherwise... well, being pirates their simple solution is to dump the unfortunate sailor into the deep blue sea and let the next pirate in line decide how to divide up the spoils.
Question: How many pirates will be thrown into the sea?
Notes:
* Pirates are smart, want money, and love life, especially their own.
* This one is harder than average. If you are stuck, think of fewer pirates...
* Why would #1 ever vote for any schemes?
* Why would #2 ever vote for any schemes?
THREE GODS - unsolved
Three gods A, B, and C are called, in some order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter. Your task is to determine the identities of A, B, and C by asking three yes-no questions; each question must be put to exactly one god. The gods understand English, but will answer all questions in their own language, in which the words for yes and no are "da" and "ja", in some order. You do not know which word means which. t could be that some god gets asked more than one question (and hence that some god is not asked any question at all).
What the second question is, and to which god it is put, may depend on the answer to the first question. (And of course similarly for the third question).
Whether Random speaks truly or not should be thought of as depending on the flip of a coin hidden in his brain: if the coin comes down heads, he speaks truly; if tails, falsely.
Random will answer "da" or "ja" when asked any yes-no question.
What the second question is, and to which god it is put, may depend on the answer to the first question. (And of course similarly for the third question).
Whether Random speaks truly or not should be thought of as depending on the flip of a coin hidden in his brain: if the coin comes down heads, he speaks truly; if tails, falsely.
Random will answer "da" or "ja" when asked any yes-no question.
ICE, ICE BABY - unsolved
You have an old-fashioned refrigerator with a small freezer compartment capable of holding seven ice cube trays stacked vertically. But there are no shelves to separate the trays, and if you stack one tray on top of another before the ice cubes in the bottom tray are fully frozen, the top tray will nestle into it, and you won't get full cubes in the bottom tray. You have an unlimited supply of trays, each of which can make a dozen cubes. What's the fastest way to make full-sized ice cubes?
They are obviously coming from a source website, but I'll try to find more when I get round to trying to solve more of them. As it is I've only made it up to River City in terms of attempting to solve the riddles.
PLEASE PUT THE NAME OF THE RIDDLE YOU ARE DISCUSSING AT THE TOP OF YOUR POST SOMEWHERE so that we know what you're talking about. I'm throwing bunches of them up at once just cuz people tend to be better at one type of riddles than others.
Finally, forumer-recommended riddles go below. I'm no pro at riddles, but I know good ones when I see them, and I will put ones that I think are good in here.
Randall_Flagg's Eye Problem - riddle source solution revealed
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."
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."
Druhim's Wheel of Misfortune - solved! - by everyone who's ever heard of the Monty Hall Problem
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?
Do you?
Redhead's Soldier Hats - solved! - kinda-sorta by Randall_Flagg, explained by Framling
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 line 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.
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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Need some stuff designed or printed? I can help with that.
the solution to three's a crowd:
Scoundrel 1 proposes dividing the $100 into three discrete amounts: $40, $35, and $25.
Scoundrel 2 agrees to the offer provided that $5 be removed from the $40 amount to make them both equal to $35.
Scoundrel 1 agrees to that concession, so they have majority.
Scoundrel 3 proposes that he picks first.
Scoundrel 2 agrees to the offer provided that he picks second.
Scoundrel 1 does not agree to the offer, but since the other two Scoundrels have majority, it is decided.
Scoundrel 3 picks one $35 amount, and Scoundrel 2 picks the other, leaving Scoundrel 1 with $25.
$5 remains, however.
Scoundrel 2 proposes dividing the $5 into three discrete amounts: 2 increments of $2, and 1 increment of $1.
Scoundrel 1 agrees to the proposition provided he gets to pick first.
Scoundrel 2 agrees with Scoundrel 1, since even if Scoundrel 1 picks first, Scoundrel 2 still has more money.
Scoundrel 3 proposes that he pick second. Scoundrel 2 refuses since that would mean Scoundrel 3 would have more money than him, but Scoundrel 1 agrees, since in either case the amount of money he ends up with is the same.
So, as a result, Scoundrel 1 takes $2, Scoundrel 3 takes $2, and Scoundrel 2 takes $1.
In the end, Scoundrel 3 ends up with $37, Scoundrel 2 ends up with $36, and Scoundrel 1 ends up with $27
The amounts are unequal, but were decided upon via a discrete offer/counter-offer matrix and majority vote, as per the riddle.
Game theory is awesome, dudes.
I have seen this exact same riddle before and solved it, although when I saw it involved a cake and not money but whatever!
Holy shit you are so goddamn retarded.
I have proven you wrong because:
In the situation you have outlined, there exists a situation in which two members get more money, therefore would vote that way, as we know for a fact that they will always take more money than less money REGARDLESS OF THE IMPLICATIONS, specifically the continuation of a bidding war. The fact that a bidding war would continue is entirely irrelevant.
That aside, the prompt said you are wrong.
That is the exact opinion I've always held of Mensa.
Seriously. I've known dudes with supposed 160 IQ that are totally fucking inept and live way less interesting/fulfilling lives than I do.
You can add rewarding to that combo too.
wait you lost me here
please be joking
if you're not joking I'll kill you
what the fuck does "regardless of the implications" mean? We are assuming that these people are rational actors, so they consider ALL OF THE IMPLICATIONS of every choice.
game theory is the coolest maths
Me too! I was actually a member for a year before I let my membership lapse.
Scoundrel 2 agrees to the offer but provides a counter-offer to modify the values, so that there are two equal increments of $35.
If he simply agrees to the offer as is, he doesn't stand to gain, and it creates a deadlock, because no scoundrel is going to knowingly agree to a proposition that involves them getting less than someone else unless that is mathematically inevitable.
By proposing to modify the values in such a fashion, Scoundrel 2 has put himself in a position that he can agree with whoever proposes to choose first, but counter-offer that he chooses second. This is is minimaxing, maximizing his benefit while minimizing his loss.
Yipee Ki Yay Motherfucker!
When I first learned of Mensa I asked my dad about it and he was all "Yeah you don't want anything to do with that bullshit."
one vote on the 35-35-25
and one vote on the 2-2-1
I guess it works
the riddle doesn't say it HAS to be one vote, but from what I can tell only one vote is supposed to take place
No, the riddle stipulates that they make offers and counter-offers and put the offers to a vote, with majority vote winning.
It does not stipulate on the number of votes, the idea of a singular vote only is implied because the guy who changed the riddle from it's original version didn't use tight enough language
Here, Viv, is the origin of the riddle in it's original version to help explain better:
http://en.wikipedia.org/wiki/Envy-free
with any thread like this you've got a danger of people doing dumb shit to appear smart, but oh well
I hadn't seen any of these before with one exception, so I like this thread
Yeah, they were giving their test one weekend back in college and I figured I'd give it a try for the hell of it. It was a fun enough experience even knowing the problems IQ tests have.
I'm having a hard time seeing how it could be done with just 3 comparisons. Obviously you start with six on each side, which tells you if there's an anomalous ball or not. However since the ball can be lighter or heavier, if there IS an anomalous ball, you still have to find it among 12, and determine it's +- status with just two comparisons, which I don't think can be done, unless I'm missing something obvious.
If you knew the +- status of the ball already it could be done by taking the unbalanced side, dividing that into two groups of 3, comparing, taking the unbalanced side, taking two out and comparing those two; if they're equal it's the missing ball, otherwise it's the unbalanced side.
But with the unknown in the +-, I'm having a hard time seeing how you can gain enough information per comparison to find the anomalous ball and it's +- status. Maybe someone else can start with this and move from there.
Why doesn't scoundrel 2 propose propose $36, $37, $27?
Satans..... hints.....
it'd be better if we all just worked it out here
The worst riddles are the ones that are like "a man with an orange hat lies dead under an oak tree, how did he die" and the answer is like "TWENTY FIVE PUPPIES...
Need some stuff designed or printed? I can help with that.
Need some stuff designed or printed? I can help with that.
I heard this one a year ago and worked on it for a while, but I couldn't get it in 3 or even imagine how it would be done
4 is doable (I think I found a couple ways to do it in 4) but there's gotta be some outside-the-box thing going on for 3 because as you said it doesn't even seem doable
those are fun