Register    Login    Search    Rss Feeds

Forums Home » Ask An Instructor » GMAT Math » General Math Questions


 Page 1 of 1 [ 4 posts ] 



  Print view Print view Previous topic Previous topic | Next topic Next topic
 

Permutation

Author Message
Ruben
 Post subject: Permutation (from score 800)
 Post Posted: Wed Sep 05, 2007 12:35 am 
Hi,

Can someone help?

Thanks

There are four contestants in the competition for 6 different prizes. Each contestant can win one prize. How many different outcomes are possible at the competition for the four contestants?

A) 15

B) 30

C) 60

D) 180

E) 360
Top 
dbernst
 Post subject:
 Post Posted: Thu Sep 06, 2007 10:32 am 
Offline
ManhattanGMAT Staff


Posts: 304
Ruben, one key to correctly answering a combinatorics problem is to identify the problem type as an arrangement (permutation) or a grouping (combination). This is simply a relatively straightforward arrangement problem.

The first contestant to win a prize has 6 potential outcomes. As this person must win one prize (no matter which prize it is), the second contestant has 5 potential outcomes. By the same logic, the third contestant has 4 potential outcomes, and the fourth contestant has 3 potential outcomes.

The total number of arrangements (permutations) is simply the product of the number of outcomes for each contestant:
6*5*4*3 = 360.

The correct answer is E.

ps. You might see other notation or approaches concerning these types of combinatorics problems (such as 6P4 or 6!/2!) but the underlying logic is identical.

Hope that helps.
-dan
Top 
mpavey
 Post subject: Contestants can win more than one prize each?
 Post Posted: Sun Feb 24, 2008 8:33 am 
The way I read this question, it is ambiguous. It sounds like it would be possible for each contestant to win more than one prize. That would mean that contestant 1 could walk away with no prizes, one prize, two prizes, ... or even all six prizes.

How would we calculate the number of possible outcomes in this case?
Top 
StaceyKoprince
 Post subject:
 Post Posted: Tue Mar 04, 2008 1:32 am 
Offline
ManhattanGMAT Staff


Posts: 6077
Location: San Francisco
"Each contestant can win one prize" is not ambiguous. Each can win one prize, period.

You won't see a question of the type you describe on the test because it would take longer than 2 minutes to calculate (without a calculator).

_________________
Stacey Koprince
Instructor
Director of Online Community
ManhattanGMAT
Top 
Display posts from previous:  Sort by  
 
 Page 1 of 1 [ 4 posts ] 





Who is online

Users browsing this forum: No registered users and 0 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: