<PRE><B>Question 310140</B>
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.
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