Find all School-related info fast with the new School-Specific MBA Forum
Learn more about the recent changes... close

It is currently 21 May 2013, 18:59
Customize  |  Hide

Search
Register
New posts
Unanswered

A certain law firm consists of 4 senior partners and 6

  Question banks Downloads My Bookmarks Reviews  
  Oldest Best Reply
Search for:
 
Print view
First unread post
Author Message
TAGS:
Director
Director
Joined: 10 Feb 2006
Posts: 671
Followers: 1

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

GMAT Tests User
A certain law firm consists of 4 senior partners and 6 [#permalink] New post 19 Nov 2007, 06:21
00:00

Question Stats:

66% (03:01) correct 33% (00:56) wrong based on 4 sessions
A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (Two groups are considered different if at least one group member is different)

48
100
120
288
600

My take :

4C1 * 6C2 + 4C2 *6C1

pLEASE ADVICE. tHANKS
_________________

GMAT the final frontie!!!.

Intern
Intern
User avatar
Joined: 02 Aug 2007
Posts: 38
Followers: 0

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

Re: PS - Combination [#permalink] New post 19 Nov 2007, 08:18
alimad wrote:
A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (Two groups are considered different if at least one group member is different)

48
100
120
288
600

My take :

4C1 * 6C2 + 4C2 *6C1

pLEASE ADVICE. tHANKS


1Senior2Juniors + 2Seniors1Junior + 3Seniors =
4C1 * 6C2 + 4C2 *6C1 + 4C3
Manager
Manager
Joined: 25 Jul 2007
Posts: 108
Followers: 1

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

Re: PS - Combination [#permalink] New post 19 Nov 2007, 08:24
alimad wrote:
A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (Two groups are considered different if at least one group member is different)

48
100
120
288
600

My take :

4C1 * 6C2 + 4C2 *6C1

pLEASE ADVICE. tHANKS


Your method is correct but you have not considered the possibility of all the 3 members of the group being senior members.
SVP
SVP
Joined: 28 Dec 2005
Posts: 1612
Followers: 1

Kudos [?]: 53 [0], given: 2

GMAT Tests User
 [#permalink] New post 19 Nov 2007, 21:13
how about this approach:

# of teams with at least 1 senior = total # of teams - # of teams with 0 senior partners

total # = 10C3

# of teams with 0 seniors = 6C3

but this didnt give me the right answer .... what am i missing ?
1 KUDOS received
SVP
SVP
Joined: 28 Dec 2005
Posts: 1612
Followers: 1

Kudos [?]: 53 [1] , given: 2

GMAT Tests User
Re: PS - Combination [#permalink] New post 20 Nov 2007, 20:25
1
This post received
KUDOS
GMATBLACKBELT wrote:
alimad wrote:
A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (Two groups are considered different if at least one group member is different)

48
100
120
288
600

My take :

4C1 * 6C2 + 4C2 *6C1

pLEASE ADVICE. tHANKS


im really lost on this problem...


What really helps me in these type of problems is to approach the thought process like this:

1. What are the total # of combinations without any restrictions ?

2. What are the total # of combinations using the OPPOSITE of the restriction ?

3. The # of combinations with the restriction is the difference between 1 and 2

So, for this question, 1 would be 10C3. 2 would be 6C3, which gives the # of ways to pick 3 ppl out of the 6 junior partners, i.e. no seniors.

The final answer should be 10C3 - 6C3
1 KUDOS received
Manager
Manager
Joined: 26 Sep 2007
Posts: 65
Followers: 1

Kudos [?]: 8 [1] , given: 5

 [#permalink] New post 21 Nov 2007, 08:48
1
This post received
KUDOS
Total no of groups of 3 members (including junior and senior) = 10C3
Total no of groups of 3 members (only juniors) = 6C3
Total no of groups of 3 members (at least 1 senior) = 10C3 - 6C3 = 120 - 20 =100
Senior Manager
Senior Manager
Joined: 06 Aug 2007
Posts: 371
Followers: 1

Kudos [?]: 19 [0], given: 0

GMAT Tests User
Re: PS - Combination [#permalink] New post 24 Nov 2007, 00:26
pmenon wrote:
GMATBLACKBELT wrote:
alimad wrote:
A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (Two groups are considered different if at least one group member is different)

48
100
120
288
600

My take :

4C1 * 6C2 + 4C2 *6C1

pLEASE ADVICE. tHANKS


im really lost on this problem...


What really helps me in these type of problems is to approach the thought process like this:

1. What are the total # of combinations without any restrictions ?

2. What are the total # of combinations using the OPPOSITE of the restriction ?

3. The # of combinations with the restriction is the difference between 1 and 2

So, for this question, 1 would be 10C3. 2 would be 6C3, which gives the # of ways to pick 3 ppl out of the 6 junior partners, i.e. no seniors.

The final answer should be 10C3 - 6C3


pmenon great explanation!! I totally lost this one.
CEO
CEO
User avatar
Joined: 21 Jan 2007
Posts: 2797
Location: New York City
Followers: 5

Kudos [?]: 132 [0], given: 4

GMAT Tests User
Re: PS - Combination [#permalink] New post 21 Feb 2008, 12:38
At least one = Total - none

At least one = 10C3 - none

None = 6C3

= 10C3 - 6C3
= 120 - 20 = 100
_________________

You tried your best and you failed miserably. The lesson is 'never try'. -Homer Simpson

SVP
SVP
User avatar
Joined: 24 Aug 2006
Posts: 2140
Followers: 2

Kudos [?]: 73 [0], given: 0

GMAT Tests User
Re: PS - Combination [#permalink] New post 21 Feb 2008, 12:47
All possibilities = 10!/7!3! = 120

So the answer will be a fewer than 120; 48 is of course too few since it's less than half, so 100 looks good enough for me.
Intern
Intern
Joined: 27 May 2008
Posts: 1
Followers: 0

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

Re: PS - Combination [#permalink] New post 05 Aug 2008, 01:06
But why 10C3 - 6C3?

Shouldn't it be 10P3 - 6P3

Bcoz the question mentions
(Two groups are considered different if at least one group member is different)

Am I missing something here...
Manager
Manager
Joined: 27 Oct 2008
Posts: 188
Followers: 1

Kudos [?]: 42 [0], given: 3

GMAT Tests User
Re: PS - Combination [#permalink] New post 27 Sep 2009, 23:30
A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (Two groups are considered different if at least one group member is different)

48
100
120
288
600


Soln:
= 4C2 * 6C1 + 4C1 *6C2 + 4C3
= 100 ways
Senior Manager
Senior Manager
User avatar
Joined: 22 Dec 2009
Posts: 368
Followers: 9

Kudos [?]: 136 [0], given: 47

GMAT ToolKit User GMAT Tests User
Re: PS - Combination [#permalink] New post 16 Feb 2010, 13:32
alimad wrote:
A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (Two groups are considered different if at least one group member is different)

48
100
120
288
600

My take :

4C1 * 6C2 + 4C2 *6C1

pLEASE ADVICE. tHANKS


Ans = Total Comb - Comb with only junior partners = 10c3 - 6c3 = 100 (B)
_________________

Cheers!
JT...........
If u like my post..... payback in Kudos!! :beer

|Do not post questions with OA|Please underline your SC questions while posting|Try posting the explanation along with your answer choice|
|For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide|


~~Better Burn Out... Than Fade Away~~

Re: PS - Combination   [#permalink] 16 Feb 2010, 13:32
    Similar topics Author Replies Last post
Similar
Topics:
 New posts A certain law firm consists of 4 senior partners and 6 M8 5 14 May 2006, 05:42
New posts A certain law firm consists of 4 senior partners and 6 getzgetzu 3 22 Jul 2006, 06:07
New posts 1 A certain law firm consists of 4 senior partners and 6 gnr646 4 10 Sep 2007, 05:52
New posts A certain law firm consists of 4 senior partners and 6 japped187 1 14 May 2008, 17:35
New posts 1 A certain law firm consists of 4 senior partners and 6 lionheart187 7 31 Aug 2008, 12:03
Display posts from previous: Sort by

A certain law firm consists of 4 senior partners and 6

  Question banks Downloads My Bookmarks Reviews  
Print view
First unread post

Moderators: Bunuel, VeritasPrepKarishma, IanStewart

Search for:


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®.

Main navigation

GMAT Resources

Partners

MBA Resources

www.gmac.com|www.mba.com