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

It is currently 27 Jul 2014, 22:15

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

There are 6 friends-- A,B,C,D,E,F. In how many ways can they

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
avatar
Joined: 17 Sep 2011
Posts: 209
Followers: 0

Kudos [?]: 18 [0], given: 8

GMAT Tests User
There are 6 friends-- A,B,C,D,E,F. In how many ways can they [#permalink] New post 31 Jan 2012, 16:37
There are 6 friends-- A,B,C,D,E,F. In how many ways can they sit in a row if

1) A is just before B.

2) A is before B.

My understanding is that for 1) it is 5 factorial (club AB as one unit ) and for 2) it is (6 factorial / 2) as out of total chances half the chances A might be before B and half the chances A might not. As there is slight difference in terms of wording 1and 2 I want to know whether my understanding is correct. Could someone please clarify ?

Thanks in advance
_________________

_________________
Giving +1 kudos is a better way of saying 'Thank You'.

Director
Director
User avatar
Status:
Joined: 24 Jul 2011
Posts: 547
GMAT 1: 780 Q51 V48
GRE 1: 1540 Q800 V740
Followers: 60

Kudos [?]: 261 [0], given: 11

Re: There are 6 friends-- A,B,C,D,E,F. In how many ways can they [#permalink] New post 31 Jan 2012, 18:54
Yes, your understanding is correct. Clubbing A and B together, A will be just before B in (6-1)! or 5! arrangements.

However, to calculate the number of arrangements where A will be before B, we divide 6! by 2 as in exactly half the arrangements, A will be before B, and in the other half B will be before A.

Note also that the number of arrangements where A will be before B has to be greater than the number of arrangements where A is just before B. This is true (120 v/s 360).
_________________

GyanOne | http://www.GyanOne.com | +91 9899831738

Get a free detailed MBA profile evaluation

Top MBA Rankings and MBA Admissions blog


Image

Manager
Manager
avatar
Joined: 17 Sep 2011
Posts: 209
Followers: 0

Kudos [?]: 18 [0], given: 8

GMAT Tests User
Re: There are 6 friends-- A,B,C,D,E,F. In how many ways can they [#permalink] New post 01 Feb 2012, 00:04
Thanks GyanOne for the reply
_________________

_________________
Giving +1 kudos is a better way of saying 'Thank You'.

Expert Post
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4587
Location: Pune, India
Followers: 1034

Kudos [?]: 4507 [0], given: 162

Re: There are 6 friends-- A,B,C,D,E,F. In how many ways can they [#permalink] New post 01 Feb 2012, 22:30
Expert's post
gpkk wrote:
There are 6 friends-- A,B,C,D,E,F. In how many ways can they sit in a row if

1) A is just before B.

2) A is before B.

My understanding is that for 1) it is 5 factorial (club AB as one unit ) and for 2) it is (6 factorial / 2) as out of total chances half the chances A might be before B and half the chances A might not. As there is slight difference in terms of wording 1and 2 I want to know whether my understanding is correct. Could someone please clarify ?

Thanks in advance


Yes, I have discussed this distinction in the following two posts:

http://www.veritasprep.com/blog/2011/10 ... ts-part-i/
http://www.veritasprep.com/blog/2011/10 ... s-part-ii/

The first post discusses questions similar to question 1 and the second one discusses questions similar to question 2. You might want to go through them to be clear about the concepts involved.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Save $100 on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Re: There are 6 friends-- A,B,C,D,E,F. In how many ways can they   [#permalink] 01 Feb 2012, 22:30
    Similar topics Author Replies Last post
Similar
Topics:
6 person sit around a table. In how many ways can they sit mahesh004 6 26 May 2006, 03:50
Mike and four friends go to a Knicks game. How many ways can desiguy 8 10 Dec 2005, 19:41
In how many ways can 6 people be arranged in a circle if a) sandman 5 25 Nov 2005, 15:26
How many ways 6 rings can be worn in 4 fingers gmat2me2 6 19 Mar 2005, 17:30
How many ways can 14 men be partitioned into 6 committes schumacher 10 12 Dec 2004, 10:47
Display posts from previous: Sort by

There are 6 friends-- A,B,C,D,E,F. In how many ways can they

  Question banks Downloads My Bookmarks Reviews Important topics  


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®.