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

It is currently 21 Aug 2014, 16:14

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

Elena purchased Brand X pens for $4.00 apiece and brand Y

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
Manager
Manager
avatar
Joined: 01 Dec 2011
Posts: 69
Followers: 0

Kudos [?]: 15 [1] , given: 12

GMAT Tests User
Elena purchased Brand X pens for $4.00 apiece and brand Y [#permalink] New post 06 Feb 2012, 02:44
1
This post received
KUDOS
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

85% (02:19) correct 15% (01:54) wrong based on 47 sessions
Elena purchased Brand X pens for $4.00 apiece and brand Y for $2.80 apiece. If Elena purchased a total of 12 of these pens for $42.00, how many brand X pens did she purchase?

A) 4
B) 5
C) 6
D) 7
E) 8
[Reveal] Spoiler: OA

_________________

http://en.wikipedia.org/wiki/Kudos


Last edited by fiendex on 06 Feb 2012, 03:04, edited 1 time in total.
Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 19041
Followers: 3363

Kudos [?]: 24469 [1] , given: 2680

Re: Elena purchased Brand X pens for $4.00 apiece and brand Y [#permalink] New post 06 Feb 2012, 02:57
1
This post received
KUDOS
Expert's post
fiendex wrote:
Elena purchased Brand X pens for $4.00 apiece and brand Y for $2.80 apiece. If Elena purchased a total of 12 of these pens for $42.00, how many brand X pens did she pruchase?

A) 4
B) 5
C) 6
D) 7
E) 8


4x+2.8y=42 --> multiply by 2.5 (to get the integers) --> 10x+7y=105 --> only one positive integers solutions x=7 and y=5 (how to solve: 7y must have the last digit of 5 in order the last digit of the sum to be 5).

Answer: D.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

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?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Joined: 01 Dec 2011
Posts: 69
Followers: 0

Kudos [?]: 15 [0], given: 12

GMAT Tests User
Re: Elena purchased Brand X pens for $4.00 apiece and brand Y [#permalink] New post 06 Feb 2012, 03:08
I took a different approach that is more intuitive to me:

4x + 2.80 (12 - x) = 42.00
4x + 33.60 - 2.80x = 42.00
1.20x = 8.40
x = 7
_________________

http://en.wikipedia.org/wiki/Kudos

Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 19041
Followers: 3363

Kudos [?]: 24469 [0], given: 2680

Re: Elena purchased Brand X pens for $4.00 apiece and brand Y [#permalink] New post 06 Feb 2012, 03:16
Expert's post
fiendex wrote:
I took a different approach that is more intuitive to me:

4x + 2.80 (12 - x) = 42.00
4x + 33.60 - 2.80x = 42.00
1.20x = 8.40
x = 7


Interestingly enough even if we were not told that Elena purchased a total of 12 items we could still solve the problem. Another non-negative solution of 10x+7y=105 is x=0 and y=15, but since x=0 is not listed then x=7 is correct answer anyway.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

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?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Joined: 31 Jan 2012
Posts: 74
Followers: 1

Kudos [?]: 17 [0], given: 2

Re: Elena purchased Brand X pens for $4.00 apiece and brand Y [#permalink] New post 06 Feb 2012, 03:39
I have been using this one which I feel is pretty simple as well.

Maximum cost of 12 units ($4 *12 pens)= 48
Difference in price between pen and pencil = 4 -2.8 = 1.2.
48 - 42 = $6
$6/1.2 = 5
You need to make 5 pen into pencil for the sum to be 42.

12 - 5 = 7 pens
Expert Post
Moderator
Moderator
User avatar
Joined: 01 Sep 2010
Posts: 2367
Followers: 266

Kudos [?]: 2245 [0], given: 690

Re: Elena purchased Brand X pens for $4.00 apiece and brand Y [#permalink] New post 02 Jun 2012, 05:25
Expert's post
Bunuel wrote:
fiendex wrote:
I took a different approach that is more intuitive to me:

4x + 2.80 (12 - x) = 42.00
4x + 33.60 - 2.80x = 42.00
1.20x = 8.40
x = 7


Interestingly enough even if we were not told that Elena purchased a total of 12 items we could still solve the problem. Another non-negative solution of 10x+7y=105 is x=0 and y=15, but since x=0 is not listed then x=7 is correct answer anyway.



I agree with Bunuel.........even though a similar problem on MGMAT guide is not sub 600 but 650 up........

40x + 28y = 420

We have 12 pens looking at the answer choices pick D : 7*40 + 28*5 = 420.......> 420 = 420. D
_________________

COLLECTION OF QUESTIONS
Quant: 1. Bunuel Signature Collection - The Next Generation 2. Bunuel Signature Collection ALL-IN-ONE WITH SOLUTIONS 3. Veritas Prep Blog PDF Version
Verbal:1. Best EXTERNAL resources to tackle the GMAT Verbal Section 2. e-GMAT's ALL CR topics-Consolidated 3. New Critical Reasoning question bank by carcass 4. Meaning/Clarity SC Question Bank by Carcass_Souvik 5. e-GMAT's ALL SC topics-Consolidated-2nd Edition 6. The best reading to improve Reading Comprehension
7. MY VERBAL QUESTION BANK

Re: Elena purchased Brand X pens for $4.00 apiece and brand Y   [#permalink] 02 Jun 2012, 05:25
    Similar topics Author Replies Last post
Similar
Topics:
5 The probability that a brand A widget is defective is x saintforlife 3 07 Oct 2013, 22:19
A store purchased a Brand C computer for the same amount tarek99 5 18 Jul 2008, 03:36
Brand X Brand Y Miles per gallon 40 36 Cost per gallon $0.80 Jamesk486 2 17 May 2007, 06:57
A store purchased a Brand C computer for the same amount ricokevin 10 26 Apr 2007, 05:53
Brand X laundry detergent sells for $2.00 a box. Brand Y chunjuwu 12 06 Mar 2005, 19:31
Display posts from previous: Sort by

Elena purchased Brand X pens for $4.00 apiece and brand Y

  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®.