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For this problem, assume the box contains 9 white balls, 5 red balls, and 5 blue balls, and that we choose two balls at random from the box.

What is the probability of neither being white given that neither is red?

2007-02-10 17:00:35 · 6 answers · asked by C 2 in Science & Mathematics Mathematics

2/21 was not the correct answer, but thanks for your help

2007-02-10 17:16:58 · update #1

10/171 was not the correct answer either, but thank you for still trying to help!!!

2007-02-10 17:21:37 · update #2

6 answers

Since all three possibilities (red, white, or blue) have no overlap, we can ignore the red balls, because we know that we are not drawing them. Thus, it becomes a situation of what is the probabilty that neither is white if there are the 14 non-red balls.

The probability the first is not white is 5/14. The probability the second is not white is 4/13 (one of the blue balls is gone). Thus, the probability neither is white given neither is red is 5/14*4/13=10/91

2007-02-10 17:37:46 · answer #1 · answered by Mr. Adkins 4 · 0 0

If my understanding is right, no white and red was pick. So...

5+5+9 = 15

5/15*4(one blue ball was picked)/14(one ball was removed from the box) = 2/21(probability of picking up a ball that is neither red nor white..)

2007-02-11 01:09:50 · answer #2 · answered by Paolo Y 2 · 0 1

Wouldn't the probability that neither is white given that neither is red be the same as the probability of drawing two blue?
(5/19 * 4/18 = 20/342 = 10/171)

2007-02-11 01:19:55 · answer #3 · answered by Tim P. 5 · 0 1

you want a finite answer right ?

since given is that no red are drawn you can just ignore the reds ( conditional probability of bayes )

so the answer is then 1 - ( [ 9*8 + 9 + 9] / 14*13 )
1 minus the chance that exactly 2 whites , exactly 1 white are drawn

2007-02-11 02:09:36 · answer #4 · answered by gjmb1960 7 · 0 1

if neither is red we can forget red balls so probability is 5/14

2007-02-11 01:26:26 · answer #5 · answered by Anonymous · 0 1

First, recall the definition of conditional probability:

P( neither white | neither red ) =
P(neither white and neither red)/P(neither red)

I forget if this is called hypergeometric or multinomial, and my books are inaccessible right now. So, someone else will need to finish this!

2007-02-11 01:10:45 · answer #6 · answered by modulo_function 7 · 0 1

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