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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 350,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

But I was wondering that yesterday. when do you use xCx?
Can someone mention examples when and when not, as to be able to recognize the pattern? Thanks!

did any of you noticed that my post was posted at 9:26 pm on Thu Oct 25, 2007 and elgo's post also on the same day one minuet after mine. but his post is ahead of mine. I am wondering, why, though its not gmat off-topic? hmm........

GMAT TIGER wrote:

bmwhype2 wrote:

There are 3 red chips and 2 blue ones. When arranged in a row, they form a certain color pattern, for example RBRRB. How many color patterns?

did any of you noticed that my post was posted at 9:26 pm on Thu Oct 25, 2007 and elgo's post also on the same day one minuet after mine. but his post is ahead of mine. I am wondering, why, though its not gmat off-topic? hmm........

GMAT TIGER wrote:

bmwhype2 wrote:

There are 3 red chips and 2 blue ones. When arranged in a row, they form a certain color pattern, for example RBRRB. How many color patterns?

10 12 24 60 100

= 5!/3!2! = 10

Is it too cold outside that people do not response, participate or discuss on a given topic? _________________

I don't think we should use C here as basics say that Combination(C) means selection and P means arrangement.

Here we're looking to arrange 5 chips, so we should be using Permutation.

Total ways of arranging 5 chips= 5!.

Since 3 chips are of same color and 2 of same and there is no way to distinguish between those of same color, i.e., u can't say which one is b1 and whoch one is b2 as all of them are identical.

would be used if we were picking various combinations of picking (3 or 2 items out of a set of 5). Obviously I am wrong.

So that I can further grasp this concept - let me ask a twist on this question. If the set of 9 balls had 4 red, 3 green abd 2 blue - how do we determine all possible ways the 9 can be laid out?

The way this is solved will help me understand how the above simpler problem was solved.

would be used if we were picking various combinations of picking (3 or 2 items out of a set of 5). Obviously I am wrong.

So that I can further grasp this concept - let me ask a twist on this question. If the set of 9 balls had 4 red, 3 green abd 2 blue - how do we determine all possible ways the 9 can be laid out?

The way this is solved will help me understand how the above simpler problem was solved.

Permutations of n things of which P1 are alike of one kind, P2 are alike of second kind, P3 are alike of third kind ...................... Pr are alike of r th kind such that: P1+P2+P3+..+Pr=n is:

\(\frac{n!}{P1!*P2!*P3!*...*Pr!}\).

For example number of permutation of the letters of the word "gmatclub" is 8! as there are 8 DISTINCT letters in this word.

Number of permutation of the letters of the word "google" is 6!/(2!2!), as there are 6 letters out of which g and o are represented twice.

In your example 9 balls out of which 4 are red, 3 green and 2 blue, would be 9!/(4!3!2!).

I believe the person was trying to understand how you get to an answer of 10.

Example is: There are 3 red chips and 2 blue ones, when arranged in a row, they form a certain color pattern, for example RBRRB. How many color patter. We know there are 5 chips = 5! there and 3! reds 2! blue. Therefore, 5!= (5*4*3*2*1)/(3! = 3*2*1) and (2!= 2*1) thus 5*4*3*2*1 / (3*2*1) (2*1) =5.4/2.1 =10

Harvard asks you to write a post interview reflection (PIR) within 24 hours of your interview. Many have said that there is little you can do in this...