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GMAT prep II - probability question

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GMAT prep II - probability question [#permalink] New post 26 Nov 2007, 13:40
Hi!
This is a pretty basic one, but I got it wrong...

Josh and Jose work at an auto repair center with 4 other workers. For a survey on health insurance, 2 of the 6 workers will be randomly chosen to be interviewed. What is the probability that both Josh and Jose will be chosen?

a) 1/15
b) 1/12
c) 1/9
d) 1/6
e) 1/3

Thanks!
:) -Jackie
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CEO
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 [#permalink] New post 26 Nov 2007, 13:56
Expert's post
A

P=1/c(2,6)=4!*2!/6!=2/30=1/15

another way:

P=1/6*1/5+1/6*1/5=1/15
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Re: GMAT prep II - probability question [#permalink] New post 26 Nov 2007, 16:34
jthong wrote:
Hi!
This is a pretty basic one, but I got it wrong...

Josh and Jose work at an auto repair center with 4 other workers. For a survey on health insurance, 2 of the 6 workers will be randomly chosen to be interviewed. What is the probability that both Josh and Jose will be chosen?

a) 1/15
b) 1/12
c) 1/9
d) 1/6
e) 1/3

Thanks!
:) -Jackie


Oops messed it up a bit.

A.

6!/4! = 30. We have J and J and then J and J. so 2/30= 1/15.
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 [#permalink] New post 16 Dec 2007, 15:44
why do we have to consider two cases, and not just have the probability as 1/6*1/5 ?
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CEO
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 [#permalink] New post 16 Dec 2007, 23:00
Expert's post
pmenon wrote:
why do we have to consider two cases, and not just have the probability as 1/6*1/5 ?


we have two cases: (Josh,Jose) and (Jose,Josh)

for (Josh,Jose): 1/6*1/5 and for (Jose,Josh): 1/6*1/5
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 [#permalink] New post 16 Dec 2007, 23:28
Late, but A:
2C2 / 6C2
  [#permalink] 16 Dec 2007, 23:28
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