Perms/combs 3U question (1 Viewer)

[stealerhat]

This question came from 2013 James Ruse Extension 1 paper. It's multiple choice, but I have no idea how to do it. Can anybody help? I have the answer circled.

 

[Elise8842]

http://tapatalk.imageshack.com/v2/14/09/10/d32bc8c3b1e8d875b9d83645c0f1c3a9.jpg[/

Bump~ don't get where that 2 in the denominator came from


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[braintic]

Don't worry - this is conditional probability - it is not in the course.