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Riddles?

  • 11-06-2006 3:00pm
    #1
    Registered Users, Registered Users 2 Posts: 6,031 ✭✭✭


    How about putting up a few riddles and people have to try solve them. Could be a great way to pass the time.


«134

Comments

  • Hosted Moderators Posts: 5,555 ✭✭✭tSubh Dearg


    Here's a famous one to get you all started:

    Why is a raven like a writing desk?


  • Closed Accounts Posts: 265 ✭✭Dec McC


    A room with no windows and just one door has 3 separate lights. Outside the room are 3 light switches. Figure out which switch is for which light. You cannot see the lights from the light switches and you have no help from others. You can switch the switches as many times as you like but you may only enter the room once. You cannot look in the door without entering. On return you must give your answer.


  • Posts: 0 [Deleted User]


    3 points are chosen at random along a square's outline. They then combine to form a triangle.
    (a)What is the probability that the centre of the square will be 'engulfed' by this triangle?
    (b)Same question, but instead of a square being used to place the three points on, they are now placed on the following:
    (i)a circle
    (ii)a triangle
    and........wait for it...
    (iii) Dodecahedron! (That's right, 3 dimensions! )
    (c)You may now choose 4 random points along the edges (not faces) of the dodecahedron. These will combine to form a tetrahedron. What is the probability that the centre of the dodecahedron will be engulfed by this tetrahedron?

    You have 15 minutes. :p


  • Registered Users, Registered Users 2 Posts: 6,031 ✭✭✭Slippin Jimmy


    Dec McC wrote:
    A room with no windows and just one door has 3 separate lights. Outside the room are 3 light switches. Figure out which switch is for which light. You cannot see the lights from the light switches and you have no help from others. You can switch the switches as many times as you like but you may only enter the room once. You cannot look in the door without entering. On return you must give your answer.


    Ehh......... Go outside the room and switch on all 3 switchs? Probablly worng, but still thats another one down.


  • Closed Accounts Posts: 265 ✭✭Dec McC


    you still dont know which switch is for which light


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  • Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 92,450 Mod ✭✭✭✭Capt'n Midnight


    The light switch one is very good.

    Please don't blurt out the answer to the one below it's quite soluble

    hatmen.gif


    Four men are lined up on some steps. About to be executed. They are all facing in the same direction. A wall seperates the fourth man from the other three.
    So to summarise :-

    * Man 1 can see men 2 and 3.
    * Man 2 can see man 3.
    * Man 3 can see none of the others.
    * Man 4 can see none of the others.

    The men are wearing hats. They are told that there are two white hats and two black hats. The men initally don't know what colour hat they are wearing. They are told to shout out the colour of the hat that they are wearing as soon as they know for certain what colour it is.

    They are not allowed to turn round.

    They are not allowed to talk to each other.

    If anyone guesses correctly they will all live, if anyone guesses incorrectly they will all die. They have two minures...

    So the question is -
    Who shout outs and when and why?


  • Registered Users, Registered Users 2 Posts: 408 ✭✭gramlab


    Light bulb 1 -- is it something like checking the heats of the bulbs each time u turn 1 on and off?


  • Registered Users, Registered Users 2 Posts: 625 ✭✭✭QuadLeo


    Dec McC wrote:
    A room with no windows and just one door has 3 separate lights. Outside the room are 3 light switches. Figure out which switch is for which light. You cannot see the lights from the light switches and you have no help from others. You can switch the switches as many times as you like but you may only enter the room once. You cannot look in the door without entering. On return you must give your answer.

    Answer:
    turn on the first switch. Leave it on for 2 minutes. turn it off. then turn on the 2nd switch. Go into the room. If the light is on its the 2nd switch. if the light is off, touch the bulb, if the bulb is hot it's the first switch, if its cold its the 3rd.


    hatmen.gif


    Four men are lined up on some steps. About to be executed. They are all facing in the same direction. A wall seperates the fourth man from the other three.
    So to summarise :-

    * Man 1 can see men 2 and 3.
    * Man 2 can see man 3.
    * Man 3 can see none of the others.
    * Man 4 can see none of the others.

    The men are wearing hats. They are told that there are two white hats and two black hats. The men initally don't know what colour hat they are wearing. They are told to shout out the colour of the hat that they are wearing as soon as they know for certain what colour it is.

    They are not allowed to turn round.

    They are not allowed to talk to each other.

    If anyone guesses correctly they will all live, if anyone guesses incorrectly they will all die. They have two minures...

    So the question is -
    Who shout outs and when and why?[/QUOTE]


    Answer:
    the second guy shouts out the answer. He thinks to himself "I can see a black hat infront of me. The guy behind me can see my hat and the black hat. So if I was wearing a black hat too, the guy behind me would see 2 black hats and shout out. He hasn't said anything so I must be wearing white.


  • Closed Accounts Posts: 265 ✭✭Dec McC


    gramlab wrote:
    Light bulb 1 -- is it something like checking the heats of the bulbs each time u turn 1 on and off?
    You might be on to something


  • Closed Accounts Posts: 265 ✭✭Dec McC


    Dec McC wrote:
    A room with no windows and just one door has 3 separate lights. Outside the room are 3 light switches. Figure out which switch is for which light. You cannot see the lights from the light switches and you have no help from others. You can switch the switches as many times as you like but you may only enter the room once. You cannot look in the door without entering. On return you must give your answer.


    Answer: switch on one switch and turn off after a minute. then turn on a different one and enter the room. The light that is lit is the one with the switch on, the one that is hot is the one that you had on for a minute and the light that is not on or hot is fed by the switch that you didn't touch.


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  • Closed Accounts Posts: 364 ✭✭BillyGoatGruff


    Yeah so thats one guy who shouts out the colour of his hat. Do the others not also have to shout the colours of their hats or is it just one guy who has to do it.


    EDIT --- sorry , just read the question again..... apologies. <slaps himself on the back of the head>


  • Closed Accounts Posts: 136 ✭✭w66w66


    There is a cup half full of water on a scale. If you put your finger into the water without touching the sides of the cup, will the scale read a different weight?


    I don't know the answer to this one and the kitchen scale is starting to look tempting, but that would be no fun.


  • Closed Accounts Posts: 113 ✭✭sticky9cd


    w66w66 wrote:
    There is a cup half full of water on a scale. If you put your finger into the water without touching the sides of the cup, will the scale read a different weight?


    I don't know the answer to this one and the kitchen scale is starting to look tempting, but that would be no fun.
    no


  • Closed Accounts Posts: 265 ✭✭Dec McC


    Anyone givin the answers to these riddles?


  • Registered Users, Registered Users 2 Posts: 1,496 ✭✭✭*Angel*


    3 points are chosen at random along a square's outline. They then combine to form a triangle.
    (a)What is the probability that the centre of the square will be 'engulfed' by this triangle?
    (b)Same question, but instead of a square being used to place the three points on, they are now placed on the following:
    (i)a circle
    (ii)a triangle
    and........wait for it...
    (iii) Dodecahedron! (That's right, 3 dimensions! )
    (c)You may now choose 4 random points along the edges (not faces) of the dodecahedron. These will combine to form a tetrahedron. What is the probability that the centre of the dodecahedron will be engulfed by this tetrahedron?

    You have 15 minutes. :p

    Is this a joke? Looks a tad hard... Do you know the answer?


  • Closed Accounts Posts: 344 ✭✭Dreamer 7


    An archeologist discovers the mummified remains of two people, after carefully unwrapping them he discovers that they are Adam and Eve.......But how did he know??:confused:


  • Registered Users, Registered Users 2 Posts: 25,009 ✭✭✭✭Wishbone Ash


    Dreamer 7 wrote:
    An archeologist discovers the mummified remains of two people, after carefully unwrapping them he discovers that they are Adam and Eve.......But how did he know??:confused:

    No navels?


  • Closed Accounts Posts: 344 ✭✭Dreamer 7


    Bingo Wishbone Ash I love that one in a pub it takes people hours to get it


  • Registered Users, Registered Users 2 Posts: 550 ✭✭✭Teg Veece


    My friend got asked this one towards the end of a 30 minute job interview :oS



    There are 3 metal flasks on a table. You can't see into any of the flasks but you know that each flask is filled with marbles.

    One flask is filled with all white marbles, one flask is filled with all black marbles and the other flask is filled with a mixture of both.

    On each flask is a label saying "White", "Black" or "Mixed" but you know that each of the labels are lying.

    You're allowed take one marble from one jar and then you must work out what colour marbles are in each of the jars.


  • Registered Users, Registered Users 2 Posts: 1,496 ✭✭✭*Angel*


    Teg Veece wrote:
    My friend got asked this one towards the end of a 30 minute job interview :oS



    There are 3 metal flasks on a table. You can't see into any of the flasks but you know that each flask is filled with marbles.

    One flask is filled with all white marbles, one flask is filled with all black marbles and the other flask is filled with a mixture of both.

    On each flask is a label saying "White", "Black" or "Mixed" but you know that each of the labels are lying.

    You're allowed take one marble from one jar and then you must work out what colour marbles are in each of the jars.

    If the labels are all incorrect then you should be able to take one out of the mixed jar knowing that it will contain just one colour, say it was white, then you'd automatically know that that was the white flask, the mixed flask would be the one labelled black and the black flask would be the one labelled white.

    This would also work if a black was found in the flask labelled mixed.


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  • Registered Users Posts: 14 hybal


    O-O-O-O O-O O <rings
    You arrive at a hotel and have 3 sets of golden rings. The first set of rings has 4 rings attached to eachother, the second set has 2 rings attached to eachother and the third only has one ring. You cannot take these sets of rings apart, exchange them for a different form of currency, and the hotel clerk has no change. You want to stay at the hotel for 7 nights, and you have to pay one gold ring for each night that you stay. You cannot pay in advance, or all at once at the end of your stay. How do you pay for your 7 nights at the hotel?


  • Registered Users, Registered Users 2 Posts: 950 ✭✭✭Feral Mutant


    Think I got it.
    Ist night: Give the hotel the one ring.
    2nd night: Give the hotel the two connected rings and they give you change of the one ring
    3rd night: Give the hotel the one ring
    4th night: Give the hotel the four connected rings, they give you change of the two connected and the one individual ring
    5th night: Give the hotel the one ring
    6th night: Give the hotel the two connected rings, they give you change of the one ring
    7th night: Give the hotel the one ring
    Weird how often the phrase "the one ring" came up in my answer.


  • Registered Users, Registered Users 2 Posts: 919 ✭✭✭timeout


    I think we should place the answer in a spoiler at the end of each riddle to save time :)
    My riddle:

    3 friends go out for a meal. At the end they get a bill of €30. Having a nice round figure the 3 friends agree to split the bill 3 ways each paying €10. When they pick up their coats on the way out the waiter returns and explains there was a mistake on the bill at which he hands them back the €5 difference.

    Being 3 close friends none want to take the €5 so instead agree to take 1 each and leave 2 to the waiter for his honsty. The problem is with the 1 back each friend only paid 9 for the meal (10 - 1 = €9). So 3*9 = €27 and €2 for the waiter is only €29. Where did the last euro go?
    This is one of those rare riddles without a true answer its all in the phrasing. My answer is that the money went to the Restaurant. The bill was only 25 afterall yet they paid 27 ;)


  • Posts: 0 [Deleted User]


    *Angel* wrote:
    Is this a joke? Looks a tad hard... Do you know the answer?


    It's no joke, well except maybe for the last few parts. :D

    Solution to both (a) and (b)(i) is
    1/4.
    Choose two points (say A and B) on the circle. Then draw a line from A through the centre until it hits the circle, and do the same from B. Call these new points A' and B'. Then in order for the triangle to contain the centre of the circle, the third point C must lie within the minor arc A'B'. This segment is the exact same size as minor arc AB. Therefore the probability of C being on minor arc A'B' is the same as it being on minor arc AB. This is equal to the proportion of the circumference that minor arc AB represents. Then all it takes it to know that any line will cover an average 90 degrees of the circle - and there's the answer (90/360).
    A similar argument also applies substituting "square" for "circle".


  • Registered Users, Registered Users 2 Posts: 6,374 ✭✭✭Gone West


    The light switch one is very good.

    Please don't blurt out the answer to the one below it's quite soluble

    hatmen.gif


    Four men are lined up on some steps. About to be executed. They are all facing in the same direction. A wall seperates the fourth man from the other three.
    So to summarise :-

    * Man 1 can see men 2 and 3.
    * Man 2 can see man 3.
    * Man 3 can see none of the others.
    * Man 4 can see none of the others.

    The men are wearing hats. They are told that there are two white hats and two black hats. The men initally don't know what colour hat they are wearing. They are told to shout out the colour of the hat that they are wearing as soon as they know for certain what colour it is.

    They are not allowed to turn round.

    They are not allowed to talk to each other.

    If anyone guesses correctly they will all live, if anyone guesses incorrectly they will all die. They have two minures...

    So the question is -
    Who shout outs and when and why?
    guy 2. because guy 1 would have known if guy 2 and 3 were the same, therefore guy2 figures out that they are not. with this piece of information, he knows that he is the opposite to the guy on front of him :)


  • Registered Users, Registered Users 2 Posts: 5,404 ✭✭✭Goodluck2me


    FuzzyLogic wrote:
    guy 2. because guy 1 would have known if guy 2 and 3 were the same, therefore guy2 figures out that they are not. with this piece of information, he knows that he is the opposite to the guy on front of him :)
    wp


  • Registered Users, Registered Users 2 Posts: 1,496 ✭✭✭*Angel*


    It's no joke, well except maybe for the last few parts. :D

    Solution to both (a) and (b)(i) is
    1/4.
    Choose two points (say A and B) on the circle. Then draw a line from A through the centre until it hits the circle, and do the same from B. Call these new points A' and B'. Then in order for the triangle to contain the centre of the circle, the third point C must lie within the minor arc A'B'. This segment is the exact same size as minor arc AB. Therefore the probability of C being on minor arc A'B' is the same as it being on minor arc AB. This is equal to the proportion of the circumference that minor arc AB represents. Then all it takes it to know that any line will cover an average 90 degrees of the circle - and there's the answer (90/360).
    A similar argument also applies substituting "square" for "circle".

    Right so, well i'd never have got it, nice one!


  • Registered Users Posts: 8 atr1000


    I am a rock group that has 4 members, all of whom are dead, one of which was assasinated. What am I?


  • Closed Accounts Posts: 136 ✭✭w66w66


    w66w66 wrote:
    There is a cup half full of water on a scale. If you put your finger into the water without touching the sides of the cup, will the scale read a different weight?
    I think the answer was yes to this one.

    answer to rock group one, I think.
    mount rushmore


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  • Registered Users, Registered Users 2 Posts: 550 ✭✭✭Teg Veece


    w66w66 wrote:
    There is a cup half full of water on a scale. If you put your finger into the water without touching the sides of the cup, will the scale read a different weight?


    I don't know the answer to this one and the kitchen scale is starting to look tempting, but that would be no fun.

    I reckon the scales would show a different weight as the bouyancy it provides your finger with must be counteracted against the scales.

    Angel, your solution was right by the way. Although try coming up with a plausable answer after being grilled for 30 min an electrical circuits!


  • Closed Accounts Posts: 472 ✭✭Metacortex


    atr1000 wrote:
    I am a rock group that has 4 members, all of whom are dead, one of which was assasinated. What am I?


    Is the answer
    'a rock group'. It would say 'who am i?' if it was looking for a band name.


  • Closed Accounts Posts: 2,174 ✭✭✭mathias


    About the restaurant one , 10 each makes thirty , then 5 euro given back between three of them would mean that 25 is paid for the meal which is 8.33 euros each. One each back from the 5 gives a total of 9.33 each paid for the meal . 9.33 x 3 equals 27.9999... or 28 . And 2 to the waiter is 30 , no issues , it all adds up.

    Where the phantom issue comes in is that its assumed that they all paid nine at some point , whereas that was never the case ,

    When the 5 was returned it was 8.3333.... each and when 1 each is given back its 9.33333...etc.

    It was never a case of 10 - 1 at any point , it can only ever have been a case of 10 - ( 5/3) , or 10 - 1.66666.... .


  • Registered Users, Registered Users 2 Posts: 476 ✭✭no leaf clover


    ok the same seven letters fill all the spaces, in the same order, so compete this sentence so it makes sense....

    the
    doctor was
    to perform the operation because he had


  • Registered Users, Registered Users 2 Posts: 7,459 ✭✭✭Blisterman


    The notable doctor was not able to perform the operation because he had no table


  • Closed Accounts Posts: 243 ✭✭vallo


    What is next in this sequence

    10
    1110
    3110
    ?


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  • Registered Users, Registered Users 2 Posts: 5,166 ✭✭✭enda1


    You have nine identical cuboid boxes each containing nine cubes. Each cuboid is labelled with a number from 1-9 and its contents (the cubes) have the same number on them as the cuboid whihch they are in.

    You are told that each inner cube weighs 1kg except the cubes from one cuboid which each weigh 1.01kg.

    You have a weighing scales capable of weighing to the accuracy of 0.01kg.

    You are only allowed make one weighing.

    How do you determine which cuboid contains the heavier cubes?


  • Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 92,450 Mod ✭✭✭✭Capt'n Midnight


    just to clarify
    so eight of the boxes will weigh 9Kg and the other box will weigh 9.09Kg


  • Registered Users, Registered Users 2 Posts: 5,166 ✭✭✭enda1


    yeah thats it. which one though???


  • Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    enda1 wrote:
    yeah thats it. which one though???
    Take one block from the first cuboid
    Two from the second
    Three from the third
    Four from the forth

    and so on

    Then weigh the 45 little cubes that you have. If the weight is 10 grammes over 45kg, it is the first cuboid which contains the heavier cubes, it it is 20 grams over-weight, then it is the second and so on and so forth.


  • Registered Users, Registered Users 2 Posts: 1,315 ✭✭✭quazzy


    vallo wrote:
    What is next in this sequence

    10
    1110
    3110
    ?

    Is it
    132110

    Reason:
    First line is one zero = 10
    2nd line describes the first. one 1 and one zero = 1110
    3rd line describes the 2nd. three 1's and one zero = 3110


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  • Closed Accounts Posts: 141 ✭✭bubthatub


    Dec McC wrote:
    A room with no windows and just one door has 3 separate lights. Outside the room are 3 light switches. Figure out which switch is for which light. You cannot see the lights from the light switches and you have no help from others. You can switch the switches as many times as you like but you may only enter the room once. You cannot look in the door without entering. On return you must give your answer.

    look trough the keyhole


  • Registered Users, Registered Users 2 Posts: 21,611 ✭✭✭✭Sam Vimes


    bubthatub wrote:
    look trough the keyhole
    na, you turn on on for a few minutes and then turn it off. then you turn another one on and walk into the room. you obviously know which switch belongs to the one thats on and the bulb that's off but still hot is for the other switch


  • Registered Users Posts: 128 ✭✭Scorpio Girl


    a man is found hanging in an empty 10 foot room. there is absoloutly nothing in the room except the man, the rope attached to the light fitting and a pool of water. how did he get the rope up to the light fitting?


  • Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    a man is found hanging in an empty 10 foot room. there is absoloutly nothing in the room except the man, the rope attached to the light fitting and a pool of water. how did he get the rope up to the light fitting?
    Standing on a block of ice


  • Registered Users Posts: 128 ✭✭Scorpio Girl


    Standing on a block of ice

    yes! i think that one is fairly simple but i know people who have spent hours trying to work it out.


  • Registered Users, Registered Users 2 Posts: 14,698 ✭✭✭✭BlitzKrieg


    Pretend you're a bus driver. You start at New York and fifty people get on.
    Then you drive to New Jersey and twenty people get off, while five get on.
    Then you go to Florida and ten people get off while fourteen get back on.
    When you get to New Mexico, twenty people leave and five more get back on.
    When you reach California everyone get's back on. How old is the bus driver?


  • Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    BlitzKrieg wrote:
    Pretend you're a bus driver. You start at New York and fifty people get on.
    Then you drive to New Jersey and twenty people get off, while five get on.
    Then you go to Florida and ten people get off while fourteen get back on.
    When you get to New Mexico, twenty people leave and five more get back on.
    When you reach California everyone get's back on. How old is the bus driver?
    69 ha ha ha ah ha ha hahah ah:D


  • Registered Users, Registered Users 2 Posts: 689 ✭✭✭JoeB-


    BlitzKrieg wrote:
    Pretend you're a bus driver. You start at New York and fifty people get on.
    Then you drive to New Jersey and twenty people get off, while five get on.
    Then you go to Florida and ten people get off while fourteen get back on.
    When you get to New Mexico, twenty people leave and five more get back on.
    When you reach California everyone get's back on. How old is the bus driver?


    spoiler: You're the bus driver so whatever age you are...


    How is the highlighting done to hide the spoilers? I just made the text white...


  • Registered Users, Registered Users 2 Posts: 689 ✭✭✭JoeB-


    Riddle.
    There are twelve identical balls... well almost twelve as one of the balls is heavier or lighter than the other eleven identical balls.

    You also have a balance and are allowed to make three comparisons in order to find out which ball is the dodgy one AND whether it is heavier or lighter than the others.


  • Closed Accounts Posts: 12,807 ✭✭✭✭Orion


    How is the highlighting done to hide the spoilers? I just made the text white...
    use [.spoiler] and [./spoiler] without the .


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