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The number of ways in which 12 students can be equally divided into three groups is(a) 5775(b) 7575(c) 7755(d) none of these |
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Answer» SO first select 4 out of 12 then again 4 out of remaining 8 then again 4 out of remaining 4 It will be 12C4* 8C4 * 4C4 = 12!/4!*4!*4! but here when you notice closely you will find that you counted same case 3! times instead of one This is a problem in this method. To avoid this you divide it by 3! in above expression. = 12!/4!*4!*4!*3! =5775 ways. bhai thank you very much |
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