room wih 7 people

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room wih 7 people

by djkvakin » Fri Dec 25, 2009 10:59 pm
In a room filled with 7 people, 4 people have exactly 1 sibling in the room and 3 people have exactly 2 siblings in the room. If two individuals are selected from the room at random, what is the probability that those two individuals are NOT siblings?

the OA is [spoiler]16/21[/spoiler]
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by papgust » Sat Dec 26, 2009 12:52 am
Check this,
https://www.beatthegmat.com/siblings-pro ... 49630.html

Please use the search before you post the qn.