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Permutation and combination

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by abcd1111 » Thu Jun 28, 2012 7:00 pm
there are 5 teachers , 4 girls students ,6 boys students . 5 teachers are required to sit in the first row ,4 girls students are required to sit in the second row , 6 boys students are requires to sit in the last row . In how many ways the sitting arrangement can be made ??
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Source: — Problem Solving |

by Anurag@Gurome » Thu Jun 28, 2012 7:06 pm
abcd1111 wrote:there are 5 teachers , 4 girls students ,6 boys students . 5 teachers are required to sit in the first row ,4 girls students are required to sit in the second row , 6 boys students are requires to sit in the last row . In how many ways the sitting arrangement can be made ??
5 teachers can be arranged among themselves in 5! = 120 ways
4 girls can be arranged among themselves in 4! = 24 ways
6 boys can be arranged among themselves in 6! = 720 ways

Hence, total number of seating arrangements = 120*24*720
Anurag Mairal, Ph.D., MBA
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by abcd1111 » Thu Jun 28, 2012 7:19 pm
Hi Anurag@Gurome thanks a lot for your explanation .
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by heymayank08 » Sat Jun 30, 2012 1:32 am
Anurag@Gurome wrote:
abcd1111 wrote: Hence, total number of seating arrangements = 120*24*720
hi anurag,
don't u think that this will be for the arrangement in which we have to arrange among teachers, boys adn girls,
shouldn't the answer be :
5!.4!.6!.(3)

*3 because their rows need to be arranged.
please correct me if i am wrong.
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by heymayank08 » Sat Jun 30, 2012 1:32 am
Anurag@Gurome wrote:
abcd1111 wrote: Hence, total number of seating arrangements = 120*24*720
hi anurag,
don't u think that this will be for the arrangement in which we have to arrange among teachers, boys adn girls,
shouldn't the answer be :
5!.4!.6!.(3)

*3 because their rows need to be arranged.
please correct me if i am wrong.
Join the discussion

by sandeep_thaparianz » Sat Jun 30, 2012 5:52 am
heymayank08 wrote:
Anurag@Gurome wrote:
abcd1111 wrote: Hence, total number of seating arrangements = 120*24*720
hi anurag,
don't u think that this will be for the arrangement in which we have to arrange among teachers, boys adn girls,
shouldn't the answer be :
5!.4!.6!.(3)

*3 because their rows need to be arranged.
please correct me if i am wrong.
It is already mentioned in question the pattern in which they are to be seated row wise.. So Drop *3 multiplication
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by heymayank08 » Sat Jun 30, 2012 11:39 pm
sandeep_thaparianz wrote:
heymayank08 wrote:
Anurag@Gurome wrote:
abcd1111 wrote: Hence, total number of seating arrangements = 120*24*720
hi anurag,
don't u think that this will be for the arrangement in which we have to arrange among teachers, boys adn girls,
shouldn't the answer be :
5!.4!.6!.(3)

*3 because their rows need to be arranged.
please correct me if i am wrong.
It is already mentioned in question the pattern in which they are to be seated row wise.. So Drop *3 multiplication
yeah thts wat i am saying..
since they are to be sated in 3 rows so the rows in thmselves can be arranged!
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by Anurag@Gurome » Sun Jul 01, 2012 1:54 am
heymayank08 wrote:hi anurag,
don't u think that this will be for the arrangement in which we have to arrange among teachers, boys adn girls,
shouldn't the answer be :
5!.4!.6!.(3)

*3 because their rows need to be arranged.
please correct me if i am wrong.
Read the question carefully.
The question says "5 teachers are required to sit in the first row ,4 girls students are required to sit in the second row , 6 boys students are requires to sit in the last row"

This means we cannot rearrange the rows.
The teachers will always seat in the first row, the girls in the second row and the boys in the third.

Hope that helps.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

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