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At a party one of the childrem invited is given 2 books as a gift. If there were 15...

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math30fail | Student, Undergraduate | Honors

Posted May 16, 2012 at 7:17 PM via web

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At a party one of the childrem invited is given 2 books as a gift. If there were 15 different books to choose from, how many different gifts were possible?

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Matthew Fonda | eNotes Employee

Posted May 16, 2012 at 8:12 PM (Answer #1)

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We are interested in the number of ways to choose 2 items from a set of 15 items. We use combinations for this:

15C2 = `((15),(2)) = (15!) / (2!*13!) = (15*14) / 2 = 105`

Therefore there are 105 total gifts possible.

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