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Each of the 25 balls in a certain box is either red, blue or

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RonPurewal
 Post subject: Re: Each of the 25 balls in a certain box is either red, blue or
 Post Posted: Sat Sep 03, 2011 9:02 pm 
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ManhattanGMAT Staff


Posts: 7146
tsiria wrote:
I just solved this problem using properties of sets:
P(A) or P(B) = P(A) + P(B) - P(both A&B)

We are told in S1: P(A&B) = 0, we still need P(A) and p(B), so S1 is insufficient

S2: gives us: P(A) - P(B), but we need P(A)+(B), so S2 is also insufficient. from s2, A and B can take multiple values.

Combining both S1 and S2 does not still provide p(A)+p(B), hence
answer is E.

Note: A stands for white, B is Even number


this looks legitimate. however, note that it's not as generalizable as the overlapping-sets methods.

still, more methods = better, so it's good to have this approach as well.
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