close

Privacy guaranteed - Your email is not shared with anyone.

probability question

Discussion in 'The Okie Corral' started by gwalchmai, Apr 18, 2012.

  1. gwalchmai

    gwalchmai Lucky Member

    Messages:
    27,133
    Likes Received:
    5,510
    Joined:
    Jan 9, 2002
    Location:
    Outside the perimeter
    If you drop a screw (2mm long by 1mm wide with a 2mm head) in a room 12ft x 16ft with 75% of the floor covered with cabinets, what is the probability of stepping on that screw? Assume a size 11, EEE shoe.

    Thanks, and please show your work. :supergrin:
     
  2. .264 magnum

    .264 magnum CLM

    Messages:
    13,395
    Likes Received:
    1,075
    Joined:
    Dec 5, 2002
    Location:
    Dallas TX
    100%.
     

  3. IndianaMatt

    IndianaMatt

    Messages:
    3,622
    Likes Received:
    44
    Joined:
    Jul 8, 2008
    DevilDog should be here soon to handle this.
     
  4. DanaT

    DanaT Pharaoh

    Messages:
    27,659
    Likes Received:
    5,456
    Joined:
    Feb 1, 2005
    Location:
    CO & Baden –Württemberg
    You are "almost" correct because he did not give an amount of tries in which to have a sucess.


    This means the limit of tries will approach infinity and therefore the probability will approach the limit (which is nearly 100% but never quite there 99.99999999999999999999999999999999999999999999999%+ but never hits 100%)

    -Dana
     
  5. USMCsilver

    USMCsilver Boat Life ©

    Messages:
    13,024
    Likes Received:
    149
    Joined:
    Oct 8, 2001
    Location:
    Middle of SC
    You forgot to add a timeframe.

    Also, can said screw roll under anything? If that the answer is yes, then your chances are better you won't screw your foot.
     
  6. cj5mrt

    cj5mrt

    Messages:
    930
    Likes Received:
    16
    Joined:
    Dec 26, 2005
    Location:
    Central FL
    In my case, if it was a screw I needed to finish a project and I had no others to replace it, there is zero chance of stepping on it, much less finding it.
     
  7. gwalchmai

    gwalchmai Lucky Member

    Messages:
    27,133
    Likes Received:
    5,510
    Joined:
    Jan 9, 2002
    Location:
    Outside the perimeter
    OK. I assumed everyone understood that I want the probability of stepping on the screw with any random step. I guess I was being optimistic... :supergrin:

    ETA: no, the screw will not roll under anything.
     
    Last edited: Apr 18, 2012
  8. Dennis in MA

    Dennis in MA Get off my lawn

    Messages:
    42,700
    Likes Received:
    2,821
    Joined:
    Aug 16, 2001
    Location:
    Taunton, MA
  9. janice6

    janice6 Silver Member

    Messages:
    38,740
    Likes Received:
    33,312
    Joined:
    Apr 4, 2006
    Location:
    minnesota
    When I drop a screw it always lands where I'm not looking.

    Then later, after fruitless efforts, I look where I should have to begin with and there it is.
     
  10. Geko45

    Geko45 Smartass Pilot CLM

    Messages:
    18,498
    Likes Received:
    2,738
    Joined:
    Nov 1, 2002
    Location:
    KCXO
    As much screw as wood screw could screw if a wood screw could screw wood.
     
  11. RayB

    RayB Retired Member

    Messages:
    9,202
    Likes Received:
    0
    Joined:
    Dec 2, 2005

    Have you slept at all in the last, say, 72-hours? :eyebrow:

    --Ray
     
  12. DanaT

    DanaT Pharaoh

    Messages:
    27,659
    Likes Received:
    5,456
    Joined:
    Feb 1, 2005
    Location:
    CO & Baden –Württemberg
    You still have not addressed if you are asking for the probability of an outcome with a single trial or if you are asking about the cumlative probability with an undefined or defined amount of trials.

    You question is much to vague to answer.

    Also, what is the underlying assumptions? Can the screw be randomally placed anywhere in the room or is it more likely to be near where it was dropped? Are you assuming the equal likelyhood of walking right next to a wall on the far side of the room as walking through the door into the room?

    Basically, this is a VERY complex scenario that you have to spacially oriented probabilities and the most likely way of solving the intersection of the two is monte-carlo simulations.

    -Dana
     
  13. SC Tiger

    SC Tiger Jive Tiger

    Messages:
    24,107
    Likes Received:
    10,859
    Joined:
    Aug 27, 2011
    Location:
    South Carolina
    It's always in the last place you looked.

    Because if you keep looking for something after you found it you've got problems.
     
  14. SC Tiger

    SC Tiger Jive Tiger

    Messages:
    24,107
    Likes Received:
    10,859
    Joined:
    Aug 27, 2011
    Location:
    South Carolina
    Point up, with it going through your foot.

    Murphy is an ***.
     
  15. jvbronco

    jvbronco

    Messages:
    150
    Likes Received:
    0
    Joined:
    Mar 9, 2012
    For those iPhone 4 owners: try saying this to Siri (the wood chuck version)- its hilarious to hear the phone repeat it.


    Outdoor Hub mobile, the outdoor information engine
     
  16. gwalchmai

    gwalchmai Lucky Member

    Messages:
    27,133
    Likes Received:
    5,510
    Joined:
    Jan 9, 2002
    Location:
    Outside the perimeter
    Single trial.
    Assume random placement
    Assume random foot placement anywhere in the room.

    You may use any modeling technique you choose. ;)
     
  17. John's 26

    John's 26

    Messages:
    506
    Likes Received:
    84
    Joined:
    May 27, 2002
    Location:
    Henderson NV
    If you're wearing shoes, less probability. Barefoot? almost certian...
     
  18. PuroMexicano

    PuroMexicano VIVA MEXICO !!!

    Messages:
    3,634
    Likes Received:
    27
    Joined:
    Jan 28, 2004
    Location:
    Monterrey, Mexico
    Your question should be the probability to finding it when looking for it vs the probabiliy of stepping on it barefoot. :rofl:


    0 to 100
     
  19. tous

    tous GET A ROPE!

    Messages:
    35,118
    Likes Received:
    40,035
    Joined:
    Jan 7, 2001
    Location:
    Plano, Texas, Republic of
    See the Markov Monte Carlo pattern for a definitive maybe. :supergrin:

    The previous posters are correct in noting that there is not enough information to make a reasonable conclusion.


    What is the length of your average stride?
     
  20. eyesnorth

    eyesnorth

    Messages:
    840
    Likes Received:
    6
    Joined:
    Jun 9, 2004
    Location:
    CT
    Are we also assuming that the screw is not looking for its way back into your hand?