|
Author |
Message |
|
TAGS:
|
|
|
Director
Status: Matriculating
Affiliations: Chicago Booth
Joined: 03 Feb 2011
Posts: 947
Followers: 10
Kudos [?]:
144
[0], given: 123
|
Question Stats:
25% (00:00) correct
75% (02:01) wrong based on 4 sessions
hey fluke - I am not able to find any tag that says - "permutation". So pls change the tag if required.  In how many different ways can the letters A, A, B, B, B, C, D, E be arranged if the letter C must be to the right of the letter D?
1,680
2,160
2,520
3,240
3,360I dont have the OA for this one. But I believe answer is A. Pls verify the reasoning.
There are 8!/(2!*3!) ways to arrange the letters - A, A, B, B, B, C, D, E. Hence half of these arrangements will have C to the right of D and vice- versa.
Total ways = 8!/(2!*3!) / 2 = 8 * 5040 / 2 * 6 * 2 = 1680. Answer A |
|
|
|
|
|
|
Math Forum Moderator
Joined: 20 Dec 2010
Posts: 2098
Followers: 109
Kudos [?]:
664
[0], given: 376
|
gmat1220 wrote: hey fluke - I am not able to find any tag that says - "permutation". So pls change the tag if required. In how many different ways can the letters A, A, B, B, B, C, D, E be arranged if the letter C must be to the right of the letter D?
1,680
2,160
2,520
3,240
3,360I dont have the OA for this one. But I believe answer is A. Pls verify the reasoning.
There are 8!/(2!*3!) ways to arrange the letters - A, A, B, B, B, C, D, E. Hence half of these arrangements will have C to the right of D and vice- versa.
Total ways = 8!/(2!*3!) / 2 = 8 * 5040 / 2 * 6 * 2 = 1680. Answer A Voila!! Your reasoning is same as Bunuel's and you know what it means!!! You have definitely attained a good level of understanding of permutations and combinations. Good job!! Discussed here: probability-q-91460.html
_________________
~fluke
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Director
Status: Matriculating
Affiliations: Chicago Booth
Joined: 03 Feb 2011
Posts: 947
Followers: 10
Kudos [?]:
144
[0], given: 123
|
Thanks fluke ! I love this forum. cheers
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
close
