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

 It is currently 03 May 2015, 04:03

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# A group of 8 friends want to play doubles tennis. How many

Author Message
TAGS:
Manager
Joined: 22 Oct 2007
Posts: 120
Followers: 1

Kudos [?]: 34 [0], given: 0

A group of 8 friends want to play doubles tennis. How many [#permalink]  17 Jun 2008, 08:10
1
This post was
BOOKMARKED
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
A group of 8 friends want to play doubles tennis. How many different ways can the group be divided into 4 teams of 2 people?

I read the C(8,2) * C(6,2) * C(4,2) * C(2,2)/4! approach

What if we modify the question in following way:

Total friends: 8
We need: 3 teams of 2, 2 and 4

What will the approach in this case?
SVP
Joined: 30 Apr 2008
Posts: 1892
Location: Oklahoma City
Schools: Hard Knocks
Followers: 34

Kudos [?]: 467 [0], given: 32

Re: PS: teams [#permalink]  17 Jun 2008, 12:25
Quote:
Total friends: 8
We need: 3 teams of 2, 2 and 4

What will the approach in this case?

C(8,2) * C(6,2) * C(4,4) / 3!

Why would it be incorrect?

The first team of is a combination of 2 things taken from 8, or C(8,2), then the next is a team of 2 taken from 6 available choices, so C(6,2), and the final team you state is a team of 4 taken from 4 available choices C(4,4). We have a total of 3 teams and we do not want to treat the order of the teams differently so we divide that by 3!. Dividing by 3! removes the number of ways that each team can be ordered because unless we do that, we count the same teams, but in different order as a different combination, which is not what the question asks for.
_________________

------------------------------------
J Allen Morris
**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$. GMAT Club Premium Membership - big benefits and savings Manager Joined: 21 Mar 2008 Posts: 244 Followers: 2 Kudos [?]: 19 [0], given: 0 Re: PS: teams [#permalink] 17 Jun 2008, 18:48 jallenmorris wrote: Why would it be incorrect? The first team of is a combination of 2 things taken from 8, or C(8,2), then the next is a team of 2 taken from 6 available choices, so C(6,2), and the final team you state is a team of 4 taken from 4 available choices C(4,4). We have a total of 3 teams and we do not want to treat the order of the teams differently so we divide that by 3!. Dividing by 3! removes the number of ways that each team can be ordered because unless we do that, we count the same teams, but in different order as a different combination, which is not what the question asks for. Good explanation Jallenmorris.. SVP Joined: 30 Apr 2008 Posts: 1892 Location: Oklahoma City Schools: Hard Knocks Followers: 34 Kudos [?]: 467 [0], given: 32 Re: PS: teams [#permalink] 18 Jun 2008, 06:25 C(8,2) * C(6,2) * C(4,4) / 3! For the explanation to the answer see my post above. _________________ ------------------------------------ J Allen Morris **I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.

GMAT Club Premium Membership - big benefits and savings

Manager
Joined: 11 Apr 2008
Posts: 129
Location: Chicago
Followers: 1

Kudos [?]: 38 [0], given: 0

Re: PS: teams [#permalink]  18 Jun 2008, 20:07
jallenmorris wrote:
C(8,2) * C(6,2) * C(4,4) / 3!

For the explanation to the answer see my post above.

I see the explanation but no answer.
_________________

Factorials were someone's attempt to make math look exciting!!!

Manager
Joined: 27 Apr 2008
Posts: 111
Followers: 1

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

Re: PS: teams [#permalink]  26 Jun 2008, 05:21
I dont see why shouldn't it be a simple 8c2.

i think u are all wrong
SVP
Joined: 30 Apr 2008
Posts: 1892
Location: Oklahoma City
Schools: Hard Knocks
Followers: 34

Kudos [?]: 467 [1] , given: 32

Re: PS: teams [#permalink]  26 Jun 2008, 05:41
1
KUDOS
First of all, which question are you referring to? There was the original question and then a subsequent question that was modified. The second question was 3 teams, First = 2 people, Second = 2 people and the 3rd = 4 people (total of 8) people.

Can you tell us which question you're talking about so we can explain ourselves?

rino wrote:
I dont see why shouldn't it be a simple 8c2.

i think u are all wrong

_________________

------------------------------------
J Allen Morris
**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a.

GMAT Club Premium Membership - big benefits and savings

Intern
Joined: 28 Feb 2008
Posts: 34
Followers: 0

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

Re: PS: teams [#permalink]  26 Jun 2008, 06:25
Jallenmorris, u rock..!...

nice explanation man...!!...
Re: PS: teams   [#permalink] 26 Jun 2008, 06:25
Similar topics Replies Last post
Similar
Topics:
1 A group of 8 friends want to play doubles tennis. How many 5 14 Nov 2010, 03:18
A group of 8 friends wants to play double tennis. How many 8 08 Jun 2008, 11:03
38 A group of 8 friends want to play doubles tennis. How many 27 10 Nov 2007, 20:43
A group of 8 friends want to play doubles tennis. How many 6 02 Nov 2005, 02:38
6 A group of 8 friends want to play doubles tennis. How many 28 02 Oct 2005, 01:51
Display posts from previous: Sort by