Prob in permutation n combination

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permutation n combination ques

The number of ways in which 12 students can be equally divided into 3 groups?? kindly solve this ques. thanx in advance

 

Replies (2)

Hi Ayisha ,

12 students to be equally divided into 3 groups i.e. 4 students into each group

For 1st group you have to select 4 students form 12 students i.e.  12C4.

For 2nd group you have to select 4 students from remaining 8 students i.e. 8C4.

For 3rd group you have to select 4 students from remaining 4 students i.e. 4C4.

Therefore total no. of ways = 12C4. ×8C4. ×4C4. =34650

But in the module the answer is given as 5775 i.e 34650 divided by 6. My teacher has told this thing. I also find no reason to divide it by 6. So the answer is 34650. In case this question comes in exam mark 5775 only.

For any confusion,ask further .

here the formula for that is n n-r n-2r C * C * C r r r ----------------- n --- ! r where n/r! means 12/4! r=12/3=3! 3! means 3*2*1=6


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