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

It is currently 24 Oct 2014, 12:53

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

A contractor combined x tons of a gravel mixture that contai

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
avatar
Joined: 24 Oct 2005
Posts: 577
Location: NYC
Followers: 1

Kudos [?]: 16 [0], given: 0

A contractor combined x tons of a gravel mixture that contai [#permalink] New post 09 Apr 2006, 15:49
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  85% (hard)

Question Stats:

43% (02:18) correct 57% (01:21) wrong based on 88 sessions
A contractor combined x tons of a gravel mixture that contained 10 percent gravel G, by weight, with y tons of a mixture that contained 2 percent gravel G, by weight, to produce z tons of a mixture that was 5 percent gravel G, by weight. What is the value of x ?

(1) y = 10
(2) z = 16

OPEN DISCUSSION OF THIS QUESTION IS HERE: a-contractor-combined-x-tons-of-a-gravel-mixture-that-102681.html
[Reveal] Spoiler: OA

_________________

Success is my only option, failure is not -- Eminem

Kaplan Promo CodeKnewton GMAT Discount CodesVeritas Prep GMAT Discount Codes
VP
VP
User avatar
Joined: 29 Apr 2003
Posts: 1408
Followers: 2

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

 [#permalink] New post 09 Apr 2006, 15:57
C

g(x) = 10/100 * x
g(y) = 2/100 * y

g(x) + g(y) = g(z) = 5/100 * z


10x + 2y = 5z

so u need both z and y to find the value of x!
Manager
Manager
avatar
Joined: 09 Apr 2006
Posts: 173
Location: Somewhere in Wisconsin!
Followers: 1

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

 [#permalink] New post 09 Apr 2006, 20:42
Considering both the cases, we get the following equations:

Gravel: 10x/100 + 2y/100 = 5z/100
Non-Gravel: 90x/100 + 98y/100 = 95z/100

Case A: y = 10
=====

10x + 20 = 5z
90x + 98y = 95z

Substituting y = 10, we can solve for x = 6


Case B: z = 16
=====

10x + 2y = 80
90x + 98y = 1520

Substituting z = 16, we can solve for x = 6.

So, (A) and (B) are independently sufficient to answer the query.

So the answer is D.
_________________

Thanks,
Zooroopa

Manager
Manager
avatar
Joined: 09 Apr 2006
Posts: 173
Location: Somewhere in Wisconsin!
Followers: 1

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

 [#permalink] New post 10 Apr 2006, 18:21
It is quite simple. Match weights of gravel and non-gravel.

Gravel --> 10% of x + 2% of y = 5% of z
Therefore everything that remains must be non-gravel or whatever constituent is used in the mixture.

So,

Non-Gravel -->

90% of x (this is what remains from the first mixture) +
98% of y (this is what remains from the second mixture) =
95% of z (this is what remains from the third mixture)


So you get the equation that you have in bold.
_________________

Thanks,
Zooroopa

Senior Manager
Senior Manager
avatar
Joined: 09 Aug 2005
Posts: 286
Followers: 1

Kudos [?]: 1 [0], given: 0

 [#permalink] New post 10 Apr 2006, 19:14
how about this

n1/n2 = (c2-cm)/(cm-c1)

c1, c2 and cm are concentrations , all given

n1 = x
n2 = y = statement A

statement b gives Z , which indirectly gives y in terms of x

So D
Senior Manager
Senior Manager
avatar
Joined: 05 Jan 2006
Posts: 383
Followers: 1

Kudos [?]: 18 [0], given: 0

 [#permalink] New post 13 Apr 2006, 00:00
D is my choice

Question gives us x+y=z and also .10x+.02y=.05z = .05(x+y)

1) gives y=10
so we can solve .10x+.02y=.05(x+y)
so sufficient

2) x+y=16 so .10x+.02y=8 ... two unique equation can solve it
so sufficient
Intern
Intern
avatar
Joined: 16 Mar 2006
Posts: 10
Location: USA
Followers: 0

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

 [#permalink] New post 14 Apr 2006, 09:33
Answer = B
Here is what i think
if you take total X + Y = Z (over all mass balance)
and 0.1X + 0.02 Y = 0.05 Z (Gravel balance)
We have 3 variable and two equations. But if you know the value of Z as in the second case, you can find out X and Y.
So I think Z = 16 should be sufficient to solve the equations.
_________________

"There is nothing as purifying as knowledge"

Director
Director
User avatar
Joined: 04 Jan 2006
Posts: 926
Followers: 1

Kudos [?]: 14 [0], given: 0

 [#permalink] New post 16 Apr 2006, 11:35
I learnt a nice way of solving mixtures today and learnt that best to rewrite the problem..

So question is: x/10 + y/50 = 5/100(x+y)
z = x+y given.

1. y = 10, subs y, you get x. Suff.. So now down to A or D.
2. z = 16, so y = 16-x, subs in the question, you get X. so suff.

Hence D...

Hopefully this helps to a lot of us.. Under time pressure to get this right is whole another thing!
Intern
Intern
avatar
Joined: 11 Aug 2013
Posts: 5
Followers: 0

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

Re: [#permalink] New post 28 Aug 2013, 03:42
Zooroopa wrote:
Considering both the cases, we get the following equations:

Gravel: 10x/100 + 2y/100 = 5z/100
Non-Gravel: 90x/100 + 98y/100 = 95z/100

Case A: y = 10
=====

10x + 20 = 5z
90x + 98y = 95z

Substituting y = 10, we can solve for x = 6


Case B: z = 16
=====

10x + 2y = 80
90x + 98y = 1520

Substituting z = 16, we can solve for x = 6.

So, (A) and (B) are independently sufficient to answer the query.

So the answer is D.
















Ohhh this is crazy...
that means you need to guess, that there is also non gravel equation suppose to be.
Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23409
Followers: 3613

Kudos [?]: 28911 [1] , given: 2871

Re: A contractor combined x tons of a gravel mixture that contai [#permalink] New post 28 Aug 2013, 08:39
1
This post received
KUDOS
Expert's post
A contractor combined x tons of a gravel mixture that contained 10 percent gravel G, by weight, with y tons of a mixture that contained 2 percent gravel G, by weight, to produce z tons of a mixture that was 5 percent gravel G, by weight. What is the value of x ?

Set the equation: 0.1x+0.02y=0.05(x+y), where x+y=z --> 5x=3y --> Q: x=?

(1) y=10 --> 5x=3y=30 --> x=6. Sufficient.

(2) z=x+y=16 --> y=16-x --> 5x=3y=3(16-x) --> x=6. Sufficient.

Answer: D.

OPEN DISCUSSION OF THIS QUESTION IS HERE: a-contractor-combined-x-tons-of-a-gravel-mixture-that-102681.html
_________________

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

Re: A contractor combined x tons of a gravel mixture that contai   [#permalink] 28 Aug 2013, 08:39
    Similar topics Author Replies Last post
Similar
Topics:
A contractor combined "x" tons of a gravel mixture that gmat9003 3 24 May 2011, 18:38
39 Experts publish their posts in the topic A contractor combined x tons of a gravel mixture that ugimba 19 28 Jan 2010, 14:07
A contractor combined x tons of a gravel mixture that Ibodullo 3 02 Sep 2009, 01:50
2 A contractor combined x tons of gravel mixture that cotained GMATBLACKBELT 9 17 Oct 2007, 18:39
A contractor combined x tons of a gravel mixture that remgeo 7 21 Mar 2006, 08:54
Display posts from previous: Sort by

A contractor combined x tons of a gravel mixture that contai

  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®.