SOLUTION: a bookshelf contains six mysteries and three biographies. two books are selected at random without replacement. a. what is the probability that both books are mysteries? b. what

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Question 310140: a bookshelf contains six mysteries and three biographies. two books are selected at random without replacement.
a. what is the probability that both books are mysteries?
b. what is the probability that one book is a mystery and the otehr is a biography?

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
a bookshelf contains six mysteries and three biographies. two books are selected at random without replacement.
a. what is the probability that both books are mysteries?
P(2 mystery) = 6C2/9C2 == 15/36 = 5/12
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b. what is the probability that one book is a mystery and the other is a biography?
1st: P(2 bio) = 3C2/9C2 = 3/36 = 1/12
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2nd: P(one of each) = 1 - [P(2 mystry) + P(2 bio)]
= 1 - [5/12 + 1/12]
= 1 - 6/12
= 1/2
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Cheers,
Stan H.