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GMAT Prep Problem solving - Interesting Probability Problem

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by krishna239455 » Sun Apr 22, 2012 9:31 pm
As per me the answer should be 1/2*1/2*1/2 = 1/8.
But this answer is incorrect.
Pls help to solve this problem.
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by Anurag@Gurome » Sun Apr 22, 2012 10:01 pm
krishna239455 wrote:As per me the answer should be 1/2*1/2*1/2 = 1/8.
But this answer is incorrect.
Pls help to solve this problem.

When the ball passes two pegs it will be either on the left or on the right route.

If ball is towards the left route, then possible number of ways = 4, out of which two will lead to cell 2
If ball is towards the right route, then possible number of ways = 4, out of which only one will lead to cell 2.

Therefore, there are a total of 8 ways out of which 2 + 1 = 3 lead to cell 2

So, required probability = [spoiler]3/8[/spoiler]

The correct answer is D.[spoiler][/spoiler]
Anurag Mairal, Ph.D., MBA
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Gurome, Inc.
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by GMATGuruNY » Mon Apr 23, 2012 3:56 am
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by [email protected] » Tue Apr 24, 2012 9:48 pm
Finally got a probability question correct. One of my weakness is Probability.

Got the answer as 3/8...
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