GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 20 Oct 2018, 08:04

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.

Close

Request Expert Reply

Confirm Cancel

In a certain classroom, there are 80 books, of which 24 are

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50005
In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 16 Jul 2012, 04:54
2
6
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

81% (01:52) correct 19% (02:07) wrong based on 911 sessions

HideShow timer Statistics

In a certain classroom, there are 80 books, of which 24 are fiction and 23 are written in Spanish. How many of the fiction books are written in Spanish?

(1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.
(2) Of the books written in Spanish, there are 5 more nonfiction books than fiction books.

Diagnostic Test
Question: 47
Page: 26
Difficulty: 650

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50005
In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 16 Jul 2012, 13:07
6
1
SOLUTION

In a certain classroom, there are 80 books, of which 24 are fiction and 23 are written in Spanish. How many of the fiction books are written in Spanish?

Given:

Image

(1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.

Image

So, \(x+x+6=24\) --> \(x=9\). Sufficient.

(2) Of the books written in Spanish, there are 5 more nonfiction books than fiction books.

Image

So, \(x+x+5=23\) --> \(x=9\). Sufficient.

Answer: D. (Total # of books is redundant information).

Hope it's clear.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

General Discussion
Manager
Manager
avatar
Joined: 28 Feb 2012
Posts: 112
Concentration: Strategy, International Business
Schools: INSEAD Jan '13
GPA: 3.9
WE: Marketing (Other)
GMAT ToolKit User
Re: In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 17 Jul 2012, 22:26
From the first statement: x+(x+6)=24, so x=9 (fiction books written in Spanish).
from st. 2: x+(x+5)=23, x=9 (fiction books written in Spanish)

Both statements separetely suff., so answer D.

I wonder why they provide total number of books (80 books), maybe i am missing something?
_________________

If you found my post useful and/or interesting - you are welcome to give kudos!

Intern
Intern
avatar
Joined: 02 Apr 2012
Posts: 2
Re: In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 17 Jul 2012, 22:50
Answer is D , as we can use both the statements to arrive at a unique solution

statement 1: (1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.

total fiction books = 24, so ( x+ x+6 = 24) where x is the fiction books in spanish

statement 2 states that
(2) Of the books written in Spanish, there are 5 more nonfiction books than fiction books.

so x + x+ 5 = 23 , where x is the fiction books in spanish

as we can arrive at a unique solution from both statements alone ... answer is d
Manager
Manager
avatar
Joined: 08 Apr 2013
Posts: 170
Re: In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 03 Dec 2013, 22:13
IT IS still ven diagram

call x= number of book fiction in spanish

we have
24-x, x and 23-x

from 1
(24-x) -x=6
we can get x
from 2
(23-x) -x =5
we can get x

oa is d
_________________

If anyone in this gmat forum is in England,Britain, pls, email to me, (thanghnvn@gmail.com) . I have some questions and need your advise. Thank a lot.

Intern
Intern
avatar
Joined: 25 Aug 2014
Posts: 7
Reviews Badge
Re: In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 22 Mar 2016, 15:59
Can some one explain this problem with proper Venn diagram ?
Current Student
avatar
S
Joined: 20 Mar 2014
Posts: 2633
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)
GMAT ToolKit User Premium Member Reviews Badge
In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 22 Mar 2016, 16:51
2
shekharshrek wrote:
Can some one explain this problem with proper Venn diagram ?


The 2X2 matrix is a variation of the venn diagram method and will help you solve the questions correctly and in lesser time than venn diagrams.

But for the sake of your question, refer to the attached image for description of the variables.


Attachment:
2016-03-22_19-44-42.jpg
2016-03-22_19-44-42.jpg [ 18.34 KiB | Viewed 5121 times ]


Spanish = b+c = 23

Fiction = a+b = 24

Per the question, total books = 80=a+b+c+d (d = not fiction and not Spanish)

The question asks us the value of b = ?

Per statement 1, a = 6+b ---> clearly sufficient, b=9

Per statement 2, c = 5+b ---> clearly sufficient, b=9

Both statements are sufficient.

D is the correct answer.

Hope this helps.

Learn good strategies to answer questions and not just solving questions blindly.
Intern
Intern
avatar
Joined: 25 Aug 2014
Posts: 7
Reviews Badge
Re: In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 23 Mar 2016, 11:43
Engr2012

Thanks , can you please focus more on the exact meaning of these 2 statements which are highlighted in accordance with the equation above.

1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.
(2) Of the books written in Spanish, there are 5 more nonfiction books than fiction books.
Current Student
avatar
S
Joined: 20 Mar 2014
Posts: 2633
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)
GMAT ToolKit User Premium Member Reviews Badge
Re: In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 23 Mar 2016, 11:59
shekharshrek wrote:
Engr2012

Thanks , can you please focus more on the exact meaning of these 2 statements which are highlighted in accordance with the equation above.

1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.
(2) Of the books written in Spanish, there are 5 more nonfiction books than fiction books.


Sure, if you look at the venn diagram, statement 1 mentions that "there are 6 more that are not written in Spanish than are written in Spanish"

---> Total fiction books = a+b, fiction + Spanish books = b , fiction and NOT Spanish = a

Thus, per the statement, fiction + NOT Spanish = 6 + (fiction+Spanish) ---> a = 6+b

Similarly, per statement 2, total Spanish books = b+c ---> Spanish ONLY = c and Spanish + fiction = b ---> c=b+5

Hope this helps.
Intern
Intern
avatar
B
Joined: 17 Jun 2017
Posts: 1
WE: Consulting (Computer Software)
GMAT ToolKit User CAT Tests
Re: In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 31 Mar 2018, 15:03
brunel - I solved this using the table method as well. However, drawing out tables 3x is quite time consuming and I cannot seem to do it in under 3 minutes. Does 3 minutes seem reasonable to you or should I be solving this quicker?

Thanks!
Director
Director
User avatar
P
Joined: 09 Mar 2016
Posts: 942
In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 20 Apr 2018, 11:09
Bunuel wrote:
SOLUTION

In a certain classroom, there are 80 books, of which 24 are fiction and 23 are written in Spanish. How many of the fiction books are written in Spanish?

Given:

Image

(1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.

Image

So, \(x+x+6=24\) --> \(x=9\). Sufficient.

(2) Of the books written in Spanish, there are 5 more nonfiction books than fiction books.

Image

So, \(x+x+5=23\) --> \(x=9\). Sufficient.

Answer: D. (Total # of books is redundant information).

Hope it's clear.


Bunuel :) why didnt you use the formulas ? :? I mean group 1 +group +2 - both +neither

Total = 80
Group 1 is fiction book = 24
Group 2 is spanish book = 23
Both Spanish Fiction = X
Neither = 33

80 = 24 +23 - X + 33

why this formula doesnt work ? pushpitkc any idea? i itemized every number memtioned in the question ? what is first right step to tackle overlapping sets ?
Senior PS Moderator
User avatar
V
Joined: 26 Feb 2016
Posts: 3188
Location: India
GPA: 3.12
Premium Member CAT Tests
In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 20 Apr 2018, 13:05
1
dave13 wrote:
Bunuel wrote:
SOLUTION

In a certain classroom, there are 80 books, of which 24 are fiction and 23 are written in Spanish. How many of the fiction books are written in Spanish?

Given:

Image

(1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.

Image

So, \(x+x+6=24\) --> \(x=9\). Sufficient.

(2) Of the books written in Spanish, there are 5 more nonfiction books than fiction books.

Image

So, \(x+x+5=23\) --> \(x=9\). Sufficient.

Answer: D. (Total # of books is redundant information).

Hope it's clear.


Bunuel :) why didnt you use the formulas ? :? I mean group 1 +group +2 - both +neither

Total = 80
Group 1 is fiction book = 24
Group 2 is spanish book = 23
Both Spanish Fiction = X
Neither = 33

80 = 24 +23 - X + 33

why this formula doesnt work ? pushpitkc any idea? i itemized every number memtioned in the question ? what is first right step to tackle overlapping sets ?


Hey dave13

I think when you are told that of the 80 books, 24 are from the genre - Fiction
and 23 of the books are written in Spanish, there could be some books which
are both from the genre fiction and written in Spanish. You are calling that x.
Till here, you are correct!

But how do you come to a conclusion that those books which are neither fiction
nor written in Spanish are 33?

If 23 books are both from the genre fiction and written in Spanish, then there
will be one book which is of the genre Fiction and not written in Spanish. The
remaining books - 56(80 - 23 - 1) in number fall in neither written in Spanish
nor of the genre fiction.

However, if each of the books written in Spanish is not from the genre Fiction,
there would be 33(80 - 23 - 24) books which are neither written in Spanish nor
of the genre fiction

So, basically, the number of books which are neither written in Spanish nor of
the genre fiction can be between 33 and 56.

Hope this explanation clears your confusion why your method is incorrect.
_________________

You've got what it takes, but it will take everything you've got

Director
Director
User avatar
P
Joined: 09 Mar 2016
Posts: 942
In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 21 Apr 2018, 14:58
pushpitkc wrote:
dave13 wrote:
Bunuel wrote:
SOLUTION

In a certain classroom, there are 80 books, of which 24 are fiction and 23 are written in Spanish. How many of the fiction books are written in Spanish?

Given:

Image

(1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.

Image

So, \(x+x+6=24\) --> \(x=9\). Sufficient.

(2) Of the books written in Spanish, there are 5 more nonfiction books than fiction books.

Image

So, \(x+x+5=23\) --> \(x=9\). Sufficient.

Answer: D. (Total # of books is redundant information).

Hope it's clear.


Bunuel :) why didnt you use the formulas ? :? I mean group 1 +group +2 - both +neither

Total = 80
Group 1 is fiction book = 24
Group 2 is spanish book = 23
Both Spanish Fiction = X
Neither = 33

80 = 24 +23 - X + 33

why this formula doesnt work ? pushpitkc any idea? i itemized every number memtioned in the question ? what is first right step to tackle overlapping sets ?


Hey dave13

I think when you are told that of the 80 books, 24 are from the genre - Fiction
and 23 of the books are written in Spanish, there could be some books which
are both from the genre fiction and written in Spanish. You are calling that x.
Till here, you are correct!

But how do you come to a conclusion that those books which are neither fiction
nor written in Spanish are 33?

If 23 books are both from the genre fiction and written in Spanish, then there
will be one book which is of the genre Fiction and not written in Spanish. The
remaining books - 56(80 - 23 - 1) in number fall in neither written in Spanish
nor of the genre fiction.

However, if each of the books written in Spanish is not from the genre Fiction,
there would be 33(80 - 23 - 24) books which are neither written in Spanish nor
of the genre fiction

So, basically, the number of books which are neither written in Spanish nor of
the genre fiction can be between 33 and 56.

Hope this explanation clears your confusion why your method is incorrect.


Hi pushpitkc

thanks for your explanation, ok now i understand that neither written in Spanish nor of
the genre fiction can be between 33 and 56 ---

that means we need to denote Neither as unknown X

so i get

Total = 80
Group 1 is fiction book = 24
Group 2 is spanish book = 23
Both Spanish Fiction = X
Neither = X

\(80 = 24 +23 - X + X\) :? again doing something wrong ... but what ? :? :)

i think i got it... so question is How many of the fiction books are written in Spanish?

(1) Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish.

let \(x\) be fiction book written in Spanish, then non Spanish fiction books are \(x+6\)

neither = y : ?

80= x+x+6.... how to write \(group 1+group 2 -both + neither\) ...still dont get :)
Senior PS Moderator
User avatar
V
Joined: 26 Feb 2016
Posts: 3188
Location: India
GPA: 3.12
Premium Member CAT Tests
Re: In a certain classroom, there are 80 books, of which 24 are  [#permalink]

Show Tags

New post 21 Apr 2018, 23:40
2
Hi dave13

You will have to have different variables to represent "Neither" and "Both Fiction and Spanish".
The equation will be written as 80 = 23 + 24 + X + Y(which cannot be solved as such)

When you try and solve the first statement, where we are told "Of the fiction books, there are 6 more
that is not written in Spanish than are written in Spanish" - if we assume the number of fiction books
that are written in Spanish to be another variable, say "s", the fiction books not written in Spanish are
"s + 6"

Now, we know that the total number of fiction books is 24.
We can now form the equation s+s+6 = 24 and solving the equation, we get s=9(which is the number of
fiction books, written in Spanish)

We can now calculate the number of fiction books that are written in Spanish using statement 1 alone.
Hence, the answer has to be A or D. Similarly, we solve for statement 2 and because the information
given in statement 2 is also enough by itself, we arrive at the solution D!
_________________

You've got what it takes, but it will take everything you've got

GMAT Club Bot
Re: In a certain classroom, there are 80 books, of which 24 are &nbs [#permalink] 21 Apr 2018, 23:40
Display posts from previous: Sort by

In a certain classroom, there are 80 books, of which 24 are

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.