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:

hey, Looks like the question is too easy for further explanation. However, i could not understand how we got that answer. Pleaseeee reply.

In how many different ways can 4 physics, 2 math and 3 chemistry books be arranged in a row so that all books of the same branch are together?

A. 1242 B. 1728 C. 1484 D. 1734 E. 1726

There are three branches, three units of books: {physics}{math}{chemistry} - aranging branches 3!;

Arranging the books within the branches: physics - 4!; math - 2!; chemistry - 3!;

Total: 3!*4!*2!*3!.

Answer: B.

Hi Bunuel, I apologize for opening a very old post but had to .. my doubt is if we are arranging 4 physics books then doesn't the arrangement will be 4!/4!, similarly math and chemistry..and over all arrangement should be just 3!..please explain where I am missing.. Thank you, Vivek.

hey, Looks like the question is too easy for further explanation. However, i could not understand how we got that answer. Pleaseeee reply.

In how many different ways can 4 physics, 2 math and 3 chemistry books be arranged in a row so that all books of the same branch are together?

A. 1242 B. 1728 C. 1484 D. 1734 E. 1726

There are three branches, three units of books: {physics}{math}{chemistry} - aranging branches 3!;

Arranging the books within the branches: physics - 4!; math - 2!; chemistry - 3!;

Total: 3!*4!*2!*3!.

Answer: B.

Hi Bunuel, I apologize for opening a very old post but had to .. my doubt is if we are arranging 4 physics books then doesn't the arrangement will be 4!/4!, similarly math and chemistry..and over all arrangement should be just 3!..please explain where I am missing.. Thank you, Vivek.

It would be so if we were told that books in each branch are identical. But that's not our case, for example, out of 2 math books one could be on algebra and another on arithmetic thus they can be arranged within math branch as {algebra}{arithmetic} or {arithmetic }{algebra}.

Re: In how many different ways can 4 physics, 2 math and 3 [#permalink]
17 Aug 2014, 23:59

Hi Bunuel !!

I am not sure why you have assumed that the books within one subject are actually different ! I believe the books can also be same , solution in that case should be 3!.

You have assumed the same in this problem :

In how many ways can 11 books on English and 9 books on French be placed in a row on a shelf so that two books on French may not be together?

Your solution was : I would offer different solution.

We have 11 English and 9 French books, no French books should be adjacent.

Imagine 11 English books in a row and empty slots like below:

*E*E*E*E*E*E*E*E*E*E*E*

Now if 9 French books would be placed in 12 empty slots, all French books will be separated by English books.

So we can "choose" 9 empty slots from 12 available for French books, which is 12C9=220.

I believe in both these questions we should consider the books to be different. But I am confused because of the two opposite approaches applied to 2 similar problems. Where should one draw the line.

Re: In how many different ways can 4 physics, 2 math and 3 [#permalink]
28 Aug 2014, 21:00

solitaryreaper wrote:

Hi Bunuel !!

I am not sure why you have assumed that the books within one subject are actually different ! I believe the books can also be same , solution in that case should be 3!.

You have assumed the same in this problem :

In how many ways can 11 books on English and 9 books on French be placed in a row on a shelf so that two books on French may not be together?

Your solution was : I would offer different solution.

We have 11 English and 9 French books, no French books should be adjacent.

Imagine 11 English books in a row and empty slots like below:

*E*E*E*E*E*E*E*E*E*E*E*

Now if 9 French books would be placed in 12 empty slots, all French books will be separated by English books.

So we can "choose" 9 empty slots from 12 available for French books, which is 12C9=220.

I believe in both these questions we should consider the books to be different. But I am confused because of the two opposite approaches applied to 2 similar problems. Where should one draw the line.

Please have a look . Thanks in advance !!!!

Thanks! Exact same query? When do we have to consider the books different and when same , if it is not explicitly stated? Experts please answer... TIA!

Re: In how many different ways can 4 physics, 2 math and 3 [#permalink]
28 Aug 2014, 21:24

tushain wrote:

solitaryreaper wrote:

Hi Bunuel !!

I am not sure why you have assumed that the books within one subject are actually different ! I believe the books can also be same , solution in that case should be 3!.

You have assumed the same in this problem :

In how many ways can 11 books on English and 9 books on French be placed in a row on a shelf so that two books on French may not be together?

Your solution was : I would offer different solution.

We have 11 English and 9 French books, no French books should be adjacent.

Imagine 11 English books in a row and empty slots like below:

*E*E*E*E*E*E*E*E*E*E*E*

Now if 9 French books would be placed in 12 empty slots, all French books will be separated by English books.

So we can "choose" 9 empty slots from 12 available for French books, which is 12C9=220.

I believe in both these questions we should consider the books to be different. But I am confused because of the two opposite approaches applied to 2 similar problems. Where should one draw the line.

Please have a look . Thanks in advance !!!!

Thanks! Exact same query? When do we have to consider the books different and when same , if it is not explicitly stated? Experts please answer... TIA!

Because then it would be unsolvable. GMAT questions ideally state this explicitly.

gmatclubot

Re: In how many different ways can 4 physics, 2 math and 3
[#permalink]
28 Aug 2014, 21:24

Social entrepreneurs aren't running charities : ‘It’s easy to think about it in terms of charity: it’s not. They are sustainable, trading, revenue-generating businesses. The benefit of them...