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Gun Problem

  1. Jan 4, 2007 #1
    u hv a gun wid 6 bullets.NOw....
    1) u take out 3 bullets in sequence one by one and revolve it.
    2) u take out 3 bullets randomly with no sequence and revolve it.

    After revolvin it.. u fire!!!
    in which case u have higher probability of bullet being fired in the first shot!!
  2. jcsd
  3. Jan 4, 2007 #2


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    Hidden: Theoretically you have the same chance, but in practice you don't because it depends on the average number of 'clicks' per revolution. When removing the 3 consecutive bullets, the next three chambers have bullets in so if the average 'revolve' is around 2 modulo 6, you have less chance of living versus the random removals, etc.
  4. Jan 4, 2007 #3
    Umm (hidden:)
    If you have 3 in sequence with cartridges inside, and the next three empty, then the distribution of weight will be off. Chances are that after spinning it, you will have the three live rounds of ammunition on the bottom, while the three empty ones on top. As long as you only fire once, you should be fine more often than if it was random.

    EDIT: I just realized the answer! You didn't ask a question, so all of these posts are pointless :biggrin:
    Last edited: Jan 4, 2007
  5. Jan 4, 2007 #4
    Depends on how the gun is held when the chambers are spun and whether or not the length of time / rotations are randomized. For instance if it was pointed straight up (even if not exactly straight up, it still would have an effect on the probability), then both instances carry the same probability if the rotation count is also random.
  6. Jan 4, 2007 #5
    LOL :rolleyes: TH'R TEH SM CHNCS, :tongue2: LOL OMG :surprised :rofl: ROFL!
  7. Jan 4, 2007 #6


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    Geez. He probably doesn't speak English all that well, so didn't know to say "in which case do...".

    Oh wait, he deserves it for that first line. :)
  8. Jan 5, 2007 #7
    It seems that the OP is not a native speaker of English. Therefore it is pedantic to adhere to the exact wording of the puzzle. Rather we should try to derive the underlying meaning. None the less, I point out that given one interpretation of the wording here, the probability is 1 in both cases. The reason I say so is that when you pull the trigger of a gun that has some empty chambers, it may not shoot. If we continue to pull the trigger until the gun shoots, then certainly a bullet will fire. Now, in a less pedantic mode, I reword the puzzle to what I think it means (well anyway, with LESS ambiguity):

    You have a revolver with 6 chambers. Consider the following two cases:
    1) There are 3 bullets in 3 contiguous chambers, the other 3 chambers being empty.
    2) There are 3 bullets in 3 chambers, not necessarily contiguous, the other 3 chambers being empty.

    In either case, you spin the cylinder and then engage it and pull the trigger. In which case do you have higher probability of a bullet being fired?

    If this is the meaning of the puzzle, and I think it is the most likely and most interesting meaning, then I don't know the answer to it. The math part is easy and way too obvious. However, there may be some aspect of the operation of revolvers that alters the probability. I assume that is why the puzzle was posed.
  9. Jan 5, 2007 #8
    I think the question is very simple, with the simple answer of equal probability.

    If it were intended to be any more complex, we need to know more in order to answer it, therefore, the "accurate" answer is unknowable beyond the simple analysis, and is useless to discuss except if you're just curious rather than trying to come up with a real answer.

    The problem is that there isn't any relevant data for a complex problem. We're assuming the gun is a revolver, but we don't know what brand or model, or year of manufacture. Or even if it's used or new, which may have an effect on the likely stopping point of the cylinder thanks to wear. We don't even know whether the gun is being held vertically or horizontally, or at some sort of other angle, where gravity may play a part. There's no information on how the barrel is spun, with what force, in what direction, and at what initial speed. We also don't know if the cylinder is engaged when it's spun, and whether or not it's re-engaged after it's spun.

    In short, it's a simple answer because the only information available is simple. If there's more data, then we can talk about a more complex solution.

    Last edited: Jan 5, 2007
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