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A right teasebrainer...

Discussion in 'Whatnots' started by Barmy Army, Oct 12, 2006.

  1. Barmy Army

    Barmy Army Simple mind, simple pleasures... Adored Veteran

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    Remove all ads!
    A plane is standing on a conveyor belt. Now, when the plane begins to move the conveyor belt also begins moving. However, this conveyor belt has a mechanism whereby it will match the speed of the plane exactly, but in the opposite direction.

    Can the plane take off? :D
     
    Barmy Army, Oct 12, 2006
    #1

  2. Late-Night Thinker Gems: 17/31
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    nope...no air current over the wings
     
    Late-Night Thinker, Oct 12, 2006
    #2
  3. T2Bruno

    T2Bruno The only source of knowledge is experience Distinguished Member ★ SPS Account Holder Adored Veteran New Server Contributor [2012] (for helping Sorcerer's Place lease a new, more powerful server!) Torment: Tides of Numenera SP Immortalizer (for helping immortalize Sorcerer's Place in the game!)

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    The wheels on an airplane have no power to them. The thrust from the engine will be sufficient to to move the bulk of the plane even with a conveyor moving the opposite direction. The wheels will be going twice as fast as they normally do at take off, but the resistance from that will not be enough to slow the plane appreciably.

    Up, up and away.
     
    T2Bruno, Oct 12, 2006
    #3
  4. Harbourboy

    Harbourboy Take thy form from off my door! Veteran Pillars of Eternity SP Immortalizer (for helping immortalize Sorcerer's Place in the game!)

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    Yeah, the wheels of a plane don't actually do anything useful other than stop the plane from scraping along the runway. You could phrase this question another way and say could the plane take off if it was sitting in slippery ice.
     
    Harbourboy, Oct 12, 2006
    #4
  5. Barmy Army

    Barmy Army Simple mind, simple pleasures... Adored Veteran

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    Heh, smart gits :) .
    Let's try this little one instead...

    In a room of people selected at random, a poll is conducted to see if ANY TWO of them share a birthday (same day and month but not year). At what point does the probability that ANY TWO share a birthday exceed 50% (in other words, how many people must there be)?
     
    Barmy Army, Oct 12, 2006
    #5
  6. Harbourboy

    Harbourboy Take thy form from off my door! Veteran Pillars of Eternity SP Immortalizer (for helping immortalize Sorcerer's Place in the game!)

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    I guess: less than you would think. Maybe 30?
     
    Harbourboy, Oct 12, 2006
    #6

  7. Argohir Gems: 10/31
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    I think it is lesser than Harbourboy's number. I think it is 20 ( seems very small to me but it is my answer)
     
    Argohir, Oct 12, 2006
    #7
  8. Blackthorne TA

    Blackthorne TA Master in his Own Mind Staff Member ★ SPS Account Holder Adored Veteran Pillars of Eternity SP Immortalizer (for helping immortalize Sorcerer's Place in the game!) New Server Contributor [2012] (for helping Sorcerer's Place lease a new, more powerful server!) Torment: Tides of Numenera SP Immortalizer (for helping immortalize Sorcerer's Place in the game!)

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    It's actually 23.

    The probability is 1 - P(no two people in the room have the same birthday).

    If there are two people, the the probability that the second person doesn't have the same birthday as the first is 364/365 (there are 364 other days in the year that are not the same as the first person).

    For three it's 364/365 * 363/365.

    And so on.

    At 23 people you reach the 50% mark that any two share the same birthday.
     
    Blackthorne TA, Oct 12, 2006
    #8
  9. Morgoth

    Morgoth La lune ne garde aucune rancune Veteran

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    23, it is called the Birthday Paradox and it has something to do with cold winters or something ;) meh
     
    Morgoth, Oct 12, 2006
    #9
  10. Montresor

    Montresor Mostly Harmless Staff Member ★ SPS Account Holder

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    Montresor, Oct 12, 2006
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  11. Thor Gems: 10/31
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    Hrmm.. I seem to recall reading about the birthday tests on soccer-fields.

    11 players at both teams, and 1 referee. 23 altogether, and indeed, seemed it did match the theory ;)
     
    Thor, Oct 13, 2006
    #11
  12. Gnarfflinger

    Gnarfflinger Wiseguy in Training

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    When that came up in Finite Mathematics, the teacher asked if we thought 2 people in the room shared a birthday. Two guys that have the same birthday immediately threw their hands up and I looked around for the girl that shared a birthday with me, but she wasn't there...
     
    Gnarfflinger, Oct 13, 2006
    #12

  13. ChickenIsGood Gems: 23/31
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    My dad has the same birthday as me (plus 32 years).
     
    ChickenIsGood, Oct 30, 2006
    #13

  14. Faraaz Gems: 26/31
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    My sister has the same b'day as me...and she's 9 years younger than me too...so does my uncle...and he's like 20 years older than me... :D

    What are the odds of that??
     
    Faraaz, Oct 30, 2006
    #14

  15. Stu Gems: 20/31
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    My grandma and my auntie have the same birthday (6/6). When my aunti decided to have a baby she made damn sure that here daughter wouldn't have the same birthdate (number of the beast and all :) )
     
    Stu, Oct 30, 2006
    #15
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