in reply to Math help

Not quite, IMHO.

Consider 2 bags with only 2 balls in each:

Ball 1 the same: 50%
Ball 2 the same (assuming ball 1 was the same): 100%

So, you have to take into account the reduced number of balls on the second pick:

Ball 1: 1/100 = 1%
Ball 2: 1/99 = 1.01%
Total odds: 0.0101%

Tom Melly, tom@tomandlu.co.uk

Replies are listed 'Best First'.
Re^2: Math help
by Anonymous Monk on Nov 27, 2006 at 11:14 UTC

    Thanks, but in my question there are 2 pairs of two bags (4 bags) and only 1 ball is drawn from any given bag, so the choice is always 1:100.

    The question is really, as these are unconnected events, is a simple product of the single bag probabilities correct?

[reply]
      hi,

      If you don't care if the balls from the first pair are equal or not, you just want that pair1/bag1=pair2/bag1 and pair1/bag2=pair2/bag2, your answer is correct. The odds are 0.0001 (0.01%).

      But if you want that pair1/bag1=pair1/bag2 and pair1/bag1=pair2/bag1 and pair1/bag2=pair2/bag2, then you will need to multiply another time, and the correct answer will be 0.000001 (0.0001%).

      TheMage
      http://themage.bliker.com
[reply]

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