Heads or Tails

Discussion in 'Computer Support' started by Plato, Dec 13, 2004.

  1. Plato

    Plato Guest

    If I took a penny and flipped it 100 times and 99 times it came up Heads
    what are the chances of it coming up Heads again on the 101st toss?

    A: 50%
    B: 75%
    C: 99%
     
    Plato, Dec 13, 2004
    #1
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  2. Plato gibbered the following deranged nonsense:
    A:50%
     
    The Old Sourdough, Dec 13, 2004
    #2
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  3. Just now learning about statistics? It's always 50%, the penny can't
    remember what it's done in the past.
     
    =?ISO-8859-1?Q?R=F4g=EAr?=, Dec 13, 2004
    #3
  4. Plato

    Harvey Gratt Guest

    Only if the penny and the experiment aren't rigged. The real question
    should be "what is the probability that the experiment is rigged given
    the data?"

    Harvey
     
    Harvey Gratt, Dec 13, 2004
    #4
  5. Plato

    Yddap Guest

    In
    99%
    :)
     
    Yddap, Dec 13, 2004
    #5
  6. Plato

    Jock Strap Guest

    A:50%. And no, it would never come up heads 99 times in a row either.
    Yes, it's theoretically possible, but practically it wouldn't happen.
     
    Jock Strap, Dec 13, 2004
    #6
  7. Plato

    Flying Tiger Guest

    Normally 50% cz lack off memory off penny,

    if it came 99 times head up, i would check the other side off penny,
    maybe head on both sides....

    F.
     
    Flying Tiger, Dec 13, 2004
    #7
  8. Plato

    Plato Guest

    False.
     
    Plato, Dec 13, 2004
    #8
  9. Plato

    Plato Guest

    Correct. For a penny to come up Heads 99% of the time it has to be
    rigged.

    The correct answer is C:

    I imagine that you Harvey dont work in a cube but have an office with a
    window :)
     
    Plato, Dec 13, 2004
    #9
  10. Plato

    Plato Guest

    False.
     
    Plato, Dec 13, 2004
    #10
  11. Plato

    Plato Guest

    False.
     
    Plato, Dec 13, 2004
    #11
  12. Plato

    Plato Guest

    It came up once in Tails tho :) You can do the same with modified dice.
     
    Plato, Dec 13, 2004
    #12
  13. Plato

    Jock Strap Guest

    Which bit? The 50% or the 99 times? And both are true, anyway.
     
    Jock Strap, Dec 13, 2004
    #13
  14. Plato

    Plato Guest

    Open your mind.
     
    Plato, Dec 13, 2004
    #14
  15. Plato

    ex cathedra Guest

    If the coin is unbiased, it's 50-50, just like always.

    However, the smart money here says the flipping is rigged since the chances
    of 99 heads in a row in an unbiased coin is one out of two to the 99th
    power...(you do the math)!

    X
     
    ex cathedra, Dec 13, 2004
    #15
  16. Plato

    Jim Scott Guest

    Agreed. Coins have no memory.
     
    Jim Scott, Dec 13, 2004
    #16
  17. Plato

    Richard Guest

    Since you've ruled out 50% as your correct answer, which it should be, that
    leaves two choices.
    So the answer to YOUR question is 75% because 99% is impossible given the
    conditions.

    Technically though, the answer is correctly 50% because there are only 2
    sides to the coin.

    Besides, the vast majority of coins will undoubtedly land on the "tail" side
    more times than not, due to the variance in the weight of each "side".

    ya think he bought that one eh?
     
    Richard, Dec 13, 2004
    #17
  18. Plato

    Trent SC Guest

    If I took a penny and flipped it 100 times and 99 times it came up Heads
    Yes, and don't confuse "mathematical probability" and "likely outcome". The
    mathematical probability is 50%, as each event (a coin toss) is a unique
    event in its own right, without influence from other events. As other
    posters have said, the coin has no memory. It is statistically possible to
    have a coin land on tails 99 times in a row. Lunatic and more unlikely than
    my scoring tonight with Kylie, but still statistically possible.

    However, if you look at the likely outcome, you are introducing
    non-mathematical elements into the calculation. I personally wouldn't put
    half the kid's college fees on tails, and I doubt if you would either, but
    there you go.
     
    Trent SC, Dec 13, 2004
    #18
  19. Plato

    anthonyberet Guest

    None of them - it could land on its edge.
    It would be very close to but lower than 50% assuming it was an
    equally-balanced coin.
    After 99 heads I would be tempted to check it wasn't a double header or a
    trick coin in some way.
    After all, what are the chances of throwing 99 heads in a row with an
    even-chance coin?
    (very, very low).
     
    anthonyberet, Dec 13, 2004
    #19
  20. Plato

    anthonyberet Guest

    It just depends how many times you throw it - a 99 run of heads is 100%
    certain with an infinite number of throws.
     
    anthonyberet, Dec 13, 2004
    #20
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