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GMAT prep Question 1

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by moutar » Sat Apr 04, 2009 2:02 pm
2/5 = 12/30

Need 18 yellow balls for P=2/5
So 19 yellow balls would give P<2/5

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by subhasis8877 » Sat Apr 04, 2009 8:32 pm
Why not 20 ball, that also give a probabality <2/5
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by kapsii » Sat Apr 04, 2009 10:14 pm
because, the question is asking to find the minimum possible number of yellow balls, which is 19.
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Re: GMAT prep Question 1

by Vemuri » Sun Apr 05, 2009 3:10 am
Given: The probability that a random ball take from the bag is blue < 2/5

What the probability of taking a blue ball? 12/(12+y) (desired outcome/total possibilities)

So, from the inputs given, 12/(12+y) < 2/5 ==> 12+y > 30 ==> y > 18. Since the question is asking for least number of yellow balls, the answer has to 19.


Good question. Thanks for posting.
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Re: GMAT prep Question 1

by KICKGMATASS123 » Mon Apr 06, 2009 6:13 am
Thanks for a good explanation! It's perfect! :P
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