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:

A contractor combined x tons of a gravel mixture that [#permalink]
28 Jan 2010, 14:07

5

This post received KUDOS

6

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

65% (hard)

Question Stats:

49% (01:43) correct
51% (00:45) wrong based on 450 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 ?

Re: x tons of a gravel mixture [#permalink]
28 Jan 2010, 15:25

16

This post received KUDOS

Expert's post

5

This post was BOOKMARKED

ugimba wrote:

119.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

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

We have to find x. If you notice, we have two equations in 3 variables, so if we are given a value for either y OR z, this is sufficient to calculate x.

Re: Gravel Mixture [#permalink]
15 Aug 2010, 23:34

lalithajob wrote:

A contractor combined x tons of a gravel mixture that contained 10% gravel G, by weight, with y tons of a mixture that contained 2% gravel G, by weight, to produce z tons of a mixture that was 5% gravel G, by weight. What is the value of x?

1. y = 10 2. z = 16

x + y = z ( x tons of mixture1 + y tons of mixture2 = z tons of combined mixture) .1x + .02y = .05z (gravel in mixture1 + gravel in mixture2 = gravel in combined mixture)

x= ?

1) y=10. 3 equations(2 from the question + 1 from answer choice) with 3 unknowns. Can solve for x. Sufficient 2) z=16. 3 equations(2 from the question + 1 from answer choice) with 3 unknowns. Can solve for x. Sufficient

Answer D _________________

___________________________________ Please give me kudos if you like my post

Re: x tons of a gravel mixture [#permalink]
17 Aug 2010, 12:05

Question: For these types of questions can you always do Z=X+Y?

This is the first question that I've seen like this. I'm not sure if I would have gone with Z=X+Y, as Z could have been the combination X+Y and some other non-gravel material

Re: mixture problem [#permalink]
11 Oct 2010, 21:35

The answer in my opinion should be D)

By condition ,

10% X + 2% Y = 5 % Z ---(1) Also X + Y = Z ---(2)

Option (A) is sufficient to get the value of X by substituting the value of Y = 10 Option (B) is sufficient to get the value of X by substituting the value of Z = 16

Re: a contractor combined x tons ofa gravel mixture [#permalink]
26 Dec 2010, 22:06

4

This post received KUDOS

Expert's post

anilnandyala wrote:

a contractor combined x tons ofa gravel mixture that contained 10% gravel g by weight with y tons of a mixture that contained 2% gravel g by weight to produce z tons of a mixture that was 5% gravel by weight. what is the value of x?

y = 10 z = 16

Using scale method here, since 10% and 2% give weighted average of 5%, x:y = 3:5 We also know x + y = z.

1. y = 10. If y = 10, x = 6 since their ratios must be 3:5. Sufficient.

2. z = 16 If sum of x and y is 16, x must be 6 and y must be 10 to give a ratio of 3:5.

If this is not intuitive, think of it this way: x : y...... x + y 3 : 5...... 8 Since 8 in ratio terms is actually 16, 3 is actually 6 and 5 is actually 10.

Answer (D)

It will be worth your while if you understand the scale method. The time saving is huge and weighted average is a concept you will need to use time and again. For explanation of scale method, check this link: http://gmatclub.com/forum/tough-ds-105651.html#p828579 _________________

The answer is D. I was flummoxed on this one since at first I thought it was C, then I looked at it closer and thought it was B. Now I see how A and B are sufficient. Crazy DS - I HATE YOU!

Re: A contractor combined x tons of a gravel mixture that [#permalink]
15 Apr 2012, 15:40

Expert's post

ad20 wrote:

Can anyone please explain on X+Y=Z in que statement. I definitely missed it and ended up with answer C Where in question it says that x+y=z?

Sure. Question says: "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."

A contractor combined x tons of a gravel mixture that contained 10 percent 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

A contractor combined x tons of a gravel mixture that contained 10 percent 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

Merging similar topics. Please refer to the discussion above.

When I wrote this original post exactly nine months ago I had no idea how things would work out and more than a little self-doubt. I was still depressed and...

YESSSSS!!!! Yesterday Duke beat Gonzaga, 52-66, and qualified for the final four!!! (what we would call semifinals in the rest of the world). For those who don’t...