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Tough and tricky 6: Probability of drawing

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Expert Post
Math Expert
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V
Joined: 02 Sep 2009
Posts: 42259

Kudos [?]: 132744 [0], given: 12371

Tough and tricky 6: Probability of drawing [#permalink]

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New post 11 Oct 2009, 18:17
Expert's post
1
This post was
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00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

86% (00:55) correct 14% (00:36) wrong based on 90 sessions

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Kudos [?]: 132744 [0], given: 12371

Senior Manager
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Joined: 18 Aug 2009
Posts: 318

Kudos [?]: 351 [0], given: 13

Re: Tough and tricky 6: Probability of drawing [#permalink]

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New post 11 Oct 2009, 18:45
Number of ways to choose Red ball = 3C1
Number of ways to choose White ball = 2C1
Total number of ways to choose 2 balls at random = 9C2

\((3C1*2C1)*2C1/9C2 = 1/3\)
Answer is C.

Kudos [?]: 351 [0], given: 13

Manager
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Kudos [?]: 35 [0], given: 5

Re: Tough and tricky 6: Probability of drawing [#permalink]

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New post 11 Oct 2009, 23:57
I think its D i.e. 4/27

we can have either RW or WR combination in successive draws.

So the probability will be (3/9 x 2/9) + (2/9 x 3/9) = 4/27

OA pls???????

Kudos [?]: 35 [0], given: 5

Intern
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Joined: 07 Oct 2009
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Kudos [?]: 13 [0], given: 0

Re: Tough and tricky 6: Probability of drawing [#permalink]

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New post 12 Oct 2009, 04:02
answer should be D

As we are replacing the balls so the probability of drawing two balls at random is 9*9

Ans = 3*2*2/(9*9)

Kudos [?]: 13 [0], given: 0

Expert Post
Math Expert
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V
Joined: 02 Sep 2009
Posts: 42259

Kudos [?]: 132744 [0], given: 12371

Re: Tough and tricky 6: Probability of drawing [#permalink]

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New post 12 Oct 2009, 09:45

Kudos [?]: 132744 [0], given: 12371

Senior Manager
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B
Affiliations: SPG
Joined: 15 Nov 2006
Posts: 320

Kudos [?]: 894 [0], given: 28

Re: Tough and tricky 6: Probability of drawing [#permalink]

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New post 11 Feb 2011, 04:43

probability of getting RW = \(\frac{3}{9}*\frac{2}{9}\)
we could have RW or WR. in both cases, we'll have a red and a white ball.

total probability = \(\frac{3}{9}*\frac{2}{9}*2 = \frac{4}{27}\)

Ans: D

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Kudos [?]: 894 [0], given: 28

Re: Tough and tricky 6: Probability of drawing   [#permalink] 11 Feb 2011, 04:43
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