A bookshelf contains six mysteries and three biographies. Two books are selected at random without replacement. What is the probability that both books are mysteries?

Question

anonymous · Answer

P(2 mystery) = 6C2/9C2 = 15/36 = 5/12
If I deserve medal then give me one

amistre64 · Answer

there is a total of:

  9!
----  ways of choosing the books
2!7!

9.8
--- = 9.4 = 36  ways total
 2

If we take away the bios and see how many ways there are of picking 2 out of 6 we get:
 
  6!       6.5
---- = --- = 3.5 = 15 ways to get only 2 mysts.
 2!4!      2

15/36 = .41666...  the probablity of pick 2 mysts is then;  41' 2/3% right?