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In a room filled with 7 people, 4 people have exactly 1 [#permalink]
23 Jun 2006, 19:38
0% (00:00) correct
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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. If two individuals are selected from the room at random, what is the probability that those two individuals are NOT friends?
E. 16/21 _________________
[quote="X & Y"]mmmm noup. Please try again. [/quote]
It is my mistake. The explaination is right,huh?
But i calculated the prob that the chosen 2 people are friends.
It is obvious that the needed prob must be 1-5/21=16/21
E it is