Respuesta :

AL2006

Before Brian starts messing with them, there are 24 balls in the bag.
9 of them are white.

-- The probability that Brian draws a white ball from the bag is  (9/24) .

If he has already drawn one white ball and put it aside, then there are
23 balls left in the bag, and 8 of them are white.

-- The probability that Brian draws a white ball from the bag this time
is  (8/23) .

So the probability of white balls on both draws is

     (9/24) x (8/23)  = 

              (72/552)  = 

                 3 / 23  =  about 13%  (rounded)


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