At a Dinner Party: GMAT Permutation and Combination

At a dinner party, 5 people are to be seated around a circular table. Two seating arrangements are considered different only when the positions of the people are different relative to each other. What is the total nummber of different possible seating arrangements for the group?

(A) 5
(B) 10
(C) 24
(D) 32
(E) 120

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35 Comments Post a Comment
  1. valmik says:

    (C) 24

  2. baji4Mba says:

    B-10

  3. DiD says:

    A

    As position diff relative to each other so everyone will be besides everyone else once

    so 5

  4. AP says:

    Take GMAT team, please provide the answer.

  5. magnus1 says:

    Come friends, the question is just asking us the number of arrangements of 5 people around a circular table.
    Do not get misled by the extra wordings !!
    The extra wordings are intended only to tell us that this is a “Permutation” problem rather than a “Combination” one.

    Answer is -
    (n-1)! = 4! = 24.
    C

    HTH
    ~magnus1

  6. bluebells says:

    can someone please provide the correct answer?

  7. bluebells says:

    i got 120

  8. sara says:

    The answer should be (5-1)! = 4! = 24
    So (C)

  9. Same as the different ways in which 5 people can be arranged in a straight line… A-B-C-D-E ::: However the case of relative posiutions deems that BCDEA is the same as ABCDE …Thus its the same as fixing a single person and moving the rest 4 around him/her
    thus 4 ! = 24

  10. A.c. says:

    Ans is C =24

    (5-1)! = 4! = 24 Different arrangements

    Regards
    A.c.

  11. vishalsmantri says:

    C

  12. Saurabh9 says:

    The answer is C.

  13. Thiago says:

    It´s a Circular Permutations question.

    C

    perhaps this link could clarify something.

    http://tutors4you.com/circularpermutations.htm

  14. tapas says:

    I think C (24) is correct

  15. rake says:

    120 is the answer acc. to me.
    let there be five persons p1 … p5
    and the chairs be c1…c5
    keep p1 in c1 and shuffle others you will get 24 (4*3*2) combinations possible.
    similarly for each persons p2 to p5 seated in c1 there are 24 combinations each
    so u get 5 * (4!) = 5*24 = 120 or you could simply say 5!.

    Pls let me know is this is wrong

  16. Alok Singh says:

    Ans is E

    because
    the 1st position can be taken by any of then means 5

    now the 1st person already have seat so the 2nd can be taken by 4 persons
    |
    |
    |
    means like that
    the total no. of combinations will be 5x4x3x2x1 = 120

  17. akash says:

    acc to me the ans is 120(E).this is a permutation question bcoz the order matters(as the position of people are different relative to each other for each arrangement).hence 5! that is 120.

  18. as1 says:

    Thanks, thiago, for the link — very helpful.
    the online “tutor” states that if rotations don’t count as original permutations, then the total # of circular permutations equals (n-1)!/2!. this question’s emphasis on where guests are seated relative to one another suggests that we’re dealing with such a problem.
    so:
    (5-1)!/2!
    4!/2!
    12 … which, of course, isn’t an option.
    take gmat team, am i misinterpreting the question? applying the wrong formula? both?

    thanks.

  19. sarah says:

    the answer is 24
    if there are n objects one circular permutation corresponds to
    of these objects correspond to n linear arrangements as
    a1,a2,a3…..an
    a2,a3,a4…an,a1
    ….until an,,…a1.these n arrangements correspond to only 1 circular permutation as in the case of the latter difference in arrangement is only becoz of change in relative position.
    let x be the number of circular permutations
    x*n=n!(the total number of arrangements of n objects)
    x=(n-1)!
    in this question 5 is the number of people hence number of cicular arrangements=4!=24

  20. sarithajennila says:

    B

  21. Tony says:

    C) 24

    Let’s name guests A,B,C,D & E

    Assume that Guest A’s place does not change at the table and always is sitting is the first spot. There are six combinations with guest B sitting to her left:
    ABCDE
    ABCED
    ABDCE
    ABDEC
    ABECD
    ABEDC

    There will be an additional six combinations for each guest. Therfore:
    4 X 6 = 24 (C)

  22. Divyesh says:

    Answer is C.. 24..

  23. rajeev dogra says:

    C 24

  24. sohan says:

    answer is C…24

  25. utk says:

    If clockwise and anti clock-wise orders are different, then total number of circular-permutations is given by (n-1)!

    therefore, (5-1)! = 24

  26. kapil says:

    ans is C
    if 5 people are to be seated in a straight row the the answer will be 5! that is 120, HOWEVER if there is a round sitting arrangement then we have to fix 1 person as base and rest 4 revolves around him so ans is (5-1)! that is 24.

  27. sushmita says:

    i think the answer is C.if we fix 1 person then the other 4 can sit in 4! ways.which is 24.option C.

  28. SHOBHIT BHARGAVA says:

    C is the one!
    24

  29. Anand says:

    circular permutations (n-1)! … its simplest of question .. so ans 24 …

  30. ejdst21 says:

    Umm, no, this is not a circular permutation problem. Neither clockwise nor counterclockwise rotations count as distinct seating arrangements. It is a “linear” permutation problem, so 5! is the answer (E).

  31. p.esc says:

    thanks thiago, that was really useful!

    the answer is (n-1)!=(5-1)!=4!=4x3x2x1=24

  32. jayesh medhe says:

    24 is the answer

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