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 500,000 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:

Re: If x, y, and z are positive numbers, is x > y > z ? [#permalink]

Show Tags

19 Jun 2006, 20:55

consultinghokie wrote:

just to clarify something here:

in the equation: xz > yz you can't simply cancel out the z's right?

because it's a unknown variable, it hides the sign, in which case you don't know if z is positive or negative... is that correct logic?

that's a good point if you dont know whether 'z' is +ve or -ve but in this case the stem already tells us that z is positive, so you are right if you cancel out z on both sides.

Re: If x, y, and z are positive numbers, is x > y > z ? [#permalink]

Show Tags

31 Oct 2011, 07:02

siddhans wrote:

runitback wrote:

We know that x > y and x > z but do not have any information about y relative to z

Therefore answer should be E, as everyone seems to agree

Is this correct way to solve ?

1) xz - yz > 0

z(x-y) > 0

z> 0 or x > y

No info about z in relation with x and y ---> Insufficient

2) y(x-z)>0

y > 0 or x > z

No info about y in terms of x and x ---> Insufficient

1 + 2 combined,

z > 0 and x > y OR z<0 and x<y

OR

y>0 and x>z OR y< 0 and x < z

Insufficient

Hence E

We are told that x,y and z are positive numbers. So you don't have to consider the second case in which the variables are negative. This approach is also fine. But you will realize that for the given conditions, it is easier to cancel out the common variable

Re: If x, y, and z are positive numbers, is x > y > z ? [#permalink]

Show Tags

31 Oct 2011, 08:18

siddhans wrote:

runitback wrote:

We know that x > y and x > z but do not have any information about y relative to z

Therefore answer should be E, as everyone seems to agree

Is this correct way to solve ?

1) xz - yz > 0

z(x-y) > 0

z> 0 or x > y

No info about z in relation with x and y ---> Insufficient

2) y(x-z)>0

y > 0 or x > z

No info about y in terms of x and x ---> Insufficient

1 + 2 combined,

z > 0 and x > y OR z<0 and x<y

OR

y>0 and x>z OR y< 0 and x < z

Insufficient

Hence E

Yes, that approach is fine. However given the time constraints, it is easier to cancel out the common variable and spend time on the tougher questions.
_________________

Aim for the sky! (800 in this case) If you like my post, please give me Kudos

No, that's not correct. You cannot subtract yx > yz from xz > yz because their signs are in the same direction (> and >).

ADDING/SUBTRACTING INEQUALITIES:

You can only add inequalities when their signs are in the same direction:

If \(a>b\) and \(c>d\) (signs in same direction: \(>\) and \(>\)) --> \(a+c>b+d\). Example: \(3<4\) and \(2<5\) --> \(3+2<4+5\).

You can only apply subtraction when their signs are in the opposite directions:

If \(a>b\) and \(c<d\) (signs in opposite direction: \(>\) and \(<\)) --> \(a-c>b-d\) (take the sign of the inequality you subtract from). Example: \(3<4\) and \(5>1\) --> \(3-5<4-1\).

Happy New Year everyone! Before I get started on this post, and well, restarted on this blog in general, I wanted to mention something. For the past several months...

It’s quickly approaching two years since I last wrote anything on this blog. A lot has happened since then. When I last posted, I had just gotten back from...

Post-MBA I became very intrigued by how senior leaders navigated their career progression. It was also at this time that I realized I learned nothing about this during my...