gmatprep ds

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by Suyog » Thu Dec 06, 2007 4:04 pm
Given: the probability of blue ball is less than 2/5 i.e 0.4

Lets consider the options given.

17 yellow balls.
Total Balls = 12 + 17 = 29
Probability of blue ball is removed - 12/29; approx 0.4, hence No

18 yellow balls.
Total Balls = 12 + 18 = 30
Probability of blue ball is removed - 12/30; 0.4
Since it is given that the Probability is less then 2/5 you can say that 19 is Ans.

To confirm...
19 yellow balls.
Total Balls = 12 + 19 = 31
Probability of blue ball is removed - 12/31; approx 0.38

Ans C.