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Thread: Combinations

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    An Urch Guru Pundit Swami Sage noney08's Avatar
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    Combinations

    Q
    Nine students are split into three equal teams to develop reports on one of three problems:
    shortage of skilled labor, violence in schools, and low standardized test scores. How many different teams of students are possible?
    (A) 5040
    (B) 1680
    (C) 1512
    (D) 504
    (E) 168

  2. #2
    An Urch Guru Pundit Swami Sage
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    Re: Combinations

    Quote Originally Posted by noney08
    Q
    Nine students are split into three equal teams to develop reports on one of three problems:
    shortage of skilled labor, violence in schools, and low standardized test scores. How many different teams of students are possible?
    (A) 5040
    (B) 1680
    (C) 1512
    (D) 504
    (E) 168
    Is it 9!/(3!*3!*3!)? = 1680 => B?

    Thanks,
    GMAT-HELP

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    Life is a Cabarnet :-) transyt7's Avatar
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    Re: Combinations

    9C3*6C3*3 = 5040 or A...
    Comments, Corrections & Suggestions are Welcome!!!

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    An Urch Guru Pundit Swami Sage
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    Re: Combinations

    Quote Originally Posted by transyt7
    9C3*6C3*3 = 5040 or A...
    Transyt, it should be 9c3*6c3*3c3 = 1680 or B.. Please check and let me know.

    Thanks,
    GMAT-HELP

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    Life is a Cabarnet :-) transyt7's Avatar
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    Re: Combinations

    Quote Originally Posted by GMAT-HELP
    Transyt, it should be 9c3*6c3*3c3 = 1680 or B.. Please check and let me know.

    Thanks,
    GMAT-HELP
    U can select 3 out of 9 in 9C3 ways
    Again, u can select 3 out of remaining 6 in 6C3 ways.
    Since u got thy groups figured out, u can assign to each group the 3 tasks in 3 ways.

    Total num of ways = (9C3*6C3) * 3 = 5040

    Am I missing something ? Please correct me ...
    Comments, Corrections & Suggestions are Welcome!!!

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    An Urch Guru Pundit Swami Sage noney08's Avatar
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    Re: Combinations

    The answer is B or 1680

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    An Urch Guru Pundit Swami Sage noney08's Avatar
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    Re: Combinations

    Quote Originally Posted by GMAT-HELP
    Is it 9!/(3!*3!*3!)? = 1680 => B?

    Thanks,
    GMAT-HELP
    How did you get this ?? could you please elaborate. THanks

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    Carpe Diem! shaq's Avatar
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    Re: Combinations

    Quote Originally Posted by transyt7
    U can select 3 out of 9 in 9C3 ways
    Again, u can select 3 out of remaining 6 in 6C3 ways.
    Since u got thy groups figured out, u can assign to each group the 3 tasks in 3 ways.

    Total num of ways = (9C3*6C3) * 3 = 5040

    Am I missing something ? Please correct me ...
    The first team you can select in in 9C3 ways
    The second team you can select in 6C3 ways
    The remaining 3 people can be selected in only 1 way ( 3C3)
    so total combinations= 9C3 * 6C3 * 3C3 = 1680

    HTH ...

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    An Urch Guru Pundit Swami Sage thebullfighter's Avatar
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    Re: Combinations

    Quote Originally Posted by transyt7
    U can select 3 out of 9 in 9C3 ways
    Again, u can select 3 out of remaining 6 in 6C3 ways.
    Since u got thy groups figured out, u can assign to each group the 3 tasks in 3 ways.

    Total num of ways = (9C3*6C3) * 3 = 5040

    Am I missing something ? Please correct me ...
    u took the third combination as 1 only.
    but transyt the red part was not required to be considered in the Q. not asked.
    U were not missing anything, rather u had something X-tra..

  10. #10
    Life is a Cabarnet :-) transyt7's Avatar
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    Re: Combinations

    Quote Originally Posted by thebullfighter
    u took the third combination as 1 only.
    but transyt the red part was not required to be considered in the Q. not asked.
    U were not missing anything, rather u had something X-tra..
    Thanx, Oh well, in haste I interpreted the question as how many different ways these groups can be assigned to given 3 tasks...OK, I get it now...
    Comments, Corrections & Suggestions are Welcome!!!

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