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probability

by GMATCRUSHER » Fri Nov 27, 2009 4:29 pm
Each of 25 balls in a certain boxis either red blue or white and has a number from 1-10 painted on it. If one ball is to be selected at random from the box what is the probability that the ball selected will be either white or have an even number painted on it

1. the probability that one ball will be both white and have an even number painted on it is 0
2. the probability that the ball will be white minus the probability that the ball will have an even number painted on it is .2
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Source: — Data Sufficiency |
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by thephoenix » Sun Nov 29, 2009 7:31 am
E?????
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by adam15 » Sun Nov 29, 2009 10:25 am
I think the answer is A,
we have 25 balls with white, red blue, and they are numbered from 1 to 10, so 5 balls are missing.
the choice 1 state that the probability that the ball chosen is white and have even number is 0 then the number the number of white balls is 5 with odd numbers, and the other choice of even number, from blue and red balls which sums to 10
the probability= 5/25+10/25=15/25=3/5.
statment two is not sufficient.
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by sunnyjohn » Mon Nov 30, 2009 6:55 pm
IMO:E

P(W U E ) = P(W) + P(E) - P(W n E)

1) P(W n E) = 0
INSUFF.

2) P(W) - P(E) = 0.2
INSUFF.
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