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In a room filled with 7 people, 4 people have exactly 1 [#permalink]
15 Jan 2008, 11:03

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0% (00:00) wrong based on 1 sessions

In a room filled with 7 people, 4 people have exactly 1 friend in the room and 3 people have exactly 2 friends in the room (Assuming that friendship is a mutual relationship, i.e. if John is Peter's friend, Peter is John's friend). If two individuals are selected from the room at random, what is the probability that those two individuals are NOT friends? A. 5/21 B.3/7 C. 4/7 D.5/7 E.16/21

Re: PS Room probability [#permalink]
16 Jan 2008, 08:28

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This is a tough question. What is the likelihood something like this will appear on the real GMAT?

JCLEONES wrote:

In a room filled with 7 people, 4 people have exactly 1 friend in the room and 3 people have exactly 2 friends in the room (Assuming that friendship is a mutual relationship, i.e. if John is Peter's friend, Peter is John's friend). If two individuals are selected from the room at random, what is the probability that those two individuals are NOT friends? A. 5/21 B.3/7 C. 4/7 D.5/7 E.16/21

Re: PS Room probability [#permalink]
16 Jan 2008, 11:20

My answer is 16/21, but it took me a long time to do it.

JCLEONES wrote:

In a room filled with 7 people, 4 people have exactly 1 friend in the room and 3 people have exactly 2 friends in the room (Assuming that friendship is a mutual relationship, i.e. if John is Peter's friend, Peter is John's friend). If two individuals are selected from the room at random, what is the probability that those two individuals are NOT friends? A. 5/21 B.3/7 C. 4/7 D.5/7 E.16/21

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