Find all School-related info fast with the new School-Specific MBA Forum

It is currently 22 Aug 2014, 19:40

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

m01-q24

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
User avatar
Joined: 05 Jan 2009
Posts: 84
Followers: 1

Kudos [?]: 9 [0], given: 2

m01-q24 [#permalink] New post 16 May 2009, 06:39
I could not understand the OE. Can anybody please explain in detail

If 5 noble knights are to be seated at a round table, then how many different ways can they be seated?

(C) 2008 GMAT Club - m01#24

120
96
60
35
24
Kaplan Promo CodeKnewton GMAT Discount CodesManhattan GMAT Discount Codes
Expert Post
Founder
Founder
User avatar
Affiliations: UA-1K, SPG-G, HH-D
Joined: 04 Dec 2002
Posts: 12068
Location: United States (WA)
GMAT 1: 750 Q49 V42
GPA: 3.5
WE: Information Technology (Hospitality and Tourism)
Followers: 2221

Kudos [?]: 8223 [0], given: 3641

GMAT ToolKit User Premium Member CAT Tests
Re: m01-q24 [#permalink] New post 24 May 2009, 23:05
Expert's post
To find the total number of Permutations for 5 knights (order matters) is 5!
However, since we have a round table and therefore a circle, then we are losing one spot and have only 4 unique combinations, so the answer is 4!

Here is a reference for C&P:
http://betterexplained.com/articles/eas ... binations/

Permutations and Combinations
Some theory and concepts
formulae-for-3-overlapping-sets-69014.html
permutations-combinations-help-is-on-the-way-10838.html
permutation-combination-and-probabilities-14706.html
_________________

Founder of GMAT Club

Just starting out with GMAT? Start here... | Want to know your GMAT Score? Try GMAT Score Estimator
Need GMAT Book Recommendations? Best GMAT Books

Co-author of the GMAT Club tests

Have a blog? Feature it on GMAT Club!

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
User avatar
Joined: 01 Aug 2008
Posts: 118
Followers: 1

Kudos [?]: 15 [0], given: 2

Re: m01-q24 [#permalink] New post 25 May 2009, 10:34
for circular arrangement always consider a reference point i.e. in the above question consider one knight as the reference point and arrange the rest of the knights w.r.t to the reference knight.

so, out of 5 knight if i take one knight as reference then i have 4 knights which i can arrange in 4! ways w.r.t the reference knight and therefore 4! is the number of possible ways.
_________________

==============================================
Do not answer without sharing the reasoning behind ur choice
-----------------------------------------------------------
Working on my weakness : GMAT Verbal
------------------------------------------------------------
Ask:
Why, What, How, When, Where, Who
==============================================

Intern
Intern
avatar
Joined: 30 May 2009
Posts: 15
Followers: 0

Kudos [?]: 1 [0], given: 0

Re: m01-q24 [#permalink] New post 30 May 2009, 20:50
I read it years ago and still remember it..

for circular arrangement of n items = (n-1)!

the answer of this question is 4! = 24
Manager
Manager
User avatar
Joined: 12 Mar 2009
Posts: 192
Followers: 1

Kudos [?]: 79 [0], given: 60

GMAT Tests User
Re: m01-q24 [#permalink] New post 07 Sep 2009, 04:39
Also Google 'circular permutations' for very good articles regarding this topic.
Senior Manager
Senior Manager
avatar
Joined: 18 Aug 2009
Posts: 333
Followers: 8

Kudos [?]: 160 [0], given: 13

GMAT Tests User
Re: m01-q24 [#permalink] New post 07 Sep 2009, 07:05
cool... Thanks a lot.
Intern
Intern
avatar
Joined: 29 Jan 2011
Posts: 7
Followers: 0

Kudos [?]: 0 [0], given: 3

GMAT Tests User
Re: m01-q24 [#permalink] New post 03 Apr 2011, 18:54
Combinations and permutations are one of my weaknesses. I got this question wrong but I think I did the math correctly and I just interpreted the problem differently. At a circular table, there are (N-1)! relative positions (i.e. one knight relative to another) but there are N! combinations if one thinks of absolute positions at a circular table (i.e. if one knight is sitting in the northernmost seat, one in the easternmost seat, etc) correct? I considered absolute positions to be different even if relative positions were the same so I answered 5! or 120.

Two questions:
(1) Is my thinking regarding absolute and relative positions correct?
(2) Whenever we see a circular table question on the GMAT should we assume they're only asking about relative position?
Manager
Manager
avatar
Joined: 14 Mar 2011
Posts: 92
Followers: 1

Kudos [?]: 1 [0], given: 3

Re: m01-q24 [#permalink] New post 21 Jun 2011, 16:20
Hi all,

The key to understand circular permutation (n objects/persons) is that we have to consider 1 object/person as fixed, then the problem become a normal permutation with n-1 objects/persons.
Intern
Intern
avatar
Joined: 16 Jun 2011
Posts: 33
Followers: 0

Kudos [?]: 1 [0], given: 6

Re: m01-q24 [#permalink] New post 21 Jun 2011, 16:35
Now let's up an (n-1)! circular questions shows up on our gmat! It's good for padding time!
Intern
Intern
avatar
Joined: 04 Aug 2011
Posts: 45
Location: United States
Concentration: Technology, Leadership
GMAT 1: 570 Q45 V25
GPA: 4
WE: Information Technology (Computer Software)
Followers: 0

Kudos [?]: 14 [0], given: 20

Re: m01-q24 [#permalink] New post 14 Jan 2012, 21:49
Simple question - In cicular permutataion n arrangement to be made - N-1 ! So answer E - 24
Re: m01-q24   [#permalink] 14 Jan 2012, 21:49
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic M01, Q24 sunman 2 29 Dec 2011, 14:55
1 m01 q24 sfeiner 6 24 Dec 2009, 13:24
M01Q24 DenisSh 1 06 Sep 2009, 23:27
M01 Q24 ThrillRide 2 07 Jul 2009, 06:26
Display posts from previous: Sort by

m01-q24

  Question banks Downloads My Bookmarks Reviews Important topics  

Moderators: Bunuel, WoundedTiger



GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.