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Combo books

by tttrn333 » Sat Sep 17, 2011 10:50 pm
3 different math books, 2 different history books, and 2 different art books. In how many ways can they be arranged on a shelf if all books of the same subject must be together?
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by gmatclubmember » Sat Sep 17, 2011 11:20 pm
tttrn333 wrote:3 different math books, 2 different history books, and 2 different art books. In how many ways can they be arranged on a shelf if all books of the same subject must be together?
3 different math books can be arranged in 6 ways , history books in 2 ways and art books in 2 ways.
Besides the 3 group of these books can be arranged in 6 ways. So total ways would be
6*6*2*2 = 144.

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by krishnasty » Sat Sep 17, 2011 11:46 pm
3 math book = 3! ways
2 art books = 2! ways
2 history books = 2! ways
now these are 3 set of books and they can be arranged in 3! ways.
Hence, the ans = 6*2*2*6 = 144 ways
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