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

It is currently 29 Aug 2015, 06:46
GMAT Club Tests

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

In a certain laboratory, chemicals are identified by a

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Director
Director
avatar
Joined: 12 Jun 2006
Posts: 532
Followers: 1

Kudos [?]: 41 [0], given: 1

In a certain laboratory, chemicals are identified by a [#permalink] New post 30 Oct 2006, 02:33
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

In a certain laboratory, chemicals are identified by a color-coding system. There are 20 different chemicals. Each one is coded with either a single color or a unique two-color pair. If the order of colors in the pairs doesn't matter, what is the minimum number of different colors needed to code all 20 chemicals with either a single color or a unique pair of colors?

5
6
7
20
40
Senior Manager
Senior Manager
avatar
Joined: 23 May 2005
Posts: 266
Location: Sing/ HK
Followers: 1

Kudos [?]: 23 [0], given: 0

 [#permalink] New post 30 Oct 2006, 04:15
My answer is 6.

For a label wiht only 1 color: 6
For a label with 2 colors: 6!/ 2!(6-2)! = 15

15+6 =21

But you can also work this out even without the mathematical computation and just counting out the possible labels.
_________________

Impossible is nothing

Manager
Manager
avatar
Joined: 29 Aug 2006
Posts: 157
Followers: 1

Kudos [?]: 5 [0], given: 0

 [#permalink] New post 30 Oct 2006, 11:12
I agree ...6 is my answer too!
Director
Director
User avatar
Joined: 09 Oct 2005
Posts: 720
Location: Madrid
Followers: 3

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

 [#permalink] New post 30 Oct 2006, 22:27
Hermione wrote:
My answer is 6.

For a label wiht only 1 color: 6
For a label with 2 colors: 6!/ 2!(6-2)! = 15

15+6 =21

But you can also work this out even without the mathematical computation and just counting out the possible labels.

Good job! agree B it is
_________________

IE IMBA 2010

  [#permalink] 30 Oct 2006, 22:27
Display posts from previous: Sort by

In a certain laboratory, chemicals are identified by a

  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®.