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Re: How many ways can it be arranged on a shelf? [#permalink]

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12 Jul 2011, 02:35

Alchemist1320 wrote:

There are 4 copies of 5 different books. In how many ways can they be arranged on a shelf?

A) 20!/4! B) 20!/5(4!) C) 20!/(4!)^5 D) 20! E) 5!

formula : The number of ways in which MN different items can be divided equally into M groups, each containing N objects and the order of the groups is important is = (mn)!/(n!)^m

Re: How many ways can it be arranged on a shelf? [#permalink]

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01 Oct 2011, 04:27

sudhir18n wrote:

Alchemist1320 wrote:

There are 4 copies of 5 different books. In how many ways can they be arranged on a shelf?

A) 20!/4! B) 20!/5(4!) C) 20!/(4!)^5 D) 20! E) 5!

formula : The number of ways in which MN different items can be divided equally into M groups, each containing N objects and the order of the groups is important is = (mn)!/(n!)^m

20!/(4!)^5= C

thnx for the formula. please tell me what is the formula if order is not important
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