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

It is currently 23 Oct 2019, 14:03

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

If 1/x-1/y=1/z, what is the value of y, in terms of x and z?

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

Hide Tags

Find Similar Topics 
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 8033
GMAT 1: 760 Q51 V42
GPA: 3.82
If 1/x-1/y=1/z, what is the value of y, in terms of x and z?  [#permalink]

Show Tags

New post 22 Feb 2019, 00:18
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

78% (01:12) correct 23% (02:24) wrong based on 40 sessions

HideShow timer Statistics

[GMAT math practice question]

If \(\frac{1}{x}-\frac{1}{y}=\frac{1}{z}\), what is the value of \(y\), in terms of \(x\) and \(z\)?

\(A. \frac{xz}{(z-x)}\)
\(B. \frac{xz}{(x-z)}\)
\(C. \frac{x}{z(z-x)}\)
\(D. \frac{z}{x(x-z)}\)
\(E. xz(z-x)\)

_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $79 for 1 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"
CEO
CEO
User avatar
D
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2978
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
Reviews Badge
If 1/x-1/y=1/z, what is the value of y, in terms of x and z?  [#permalink]

Show Tags

New post 22 Feb 2019, 01:22
MathRevolution wrote:
[GMAT math practice question]

If \(\frac{1}{x}-\frac{1}{y}=\frac{1}{z}\), what is the value of \(y\), in terms of \(x\) and \(z\)?

\(A. \frac{xz}{(z-x)}\)
\(B. \frac{xz}{(x-z)}\)
\(C. \frac{x}{z(z-x)}\)
\(D. \frac{z}{x(x-z)}\)
\(E. xz(z-x)\)


\(\frac{1}{x}-\frac{1}{y}=\frac{1}{z}\)

\(\frac{1}{x}-\frac{1}{z}=\frac{1}{y}\)

\(\frac{(z-x)}{zx}=\frac{1}{y}\)

Taking reciprocal at both sides.

\(\frac{zx}{(z-x)}=y\)

Answer: Option A
_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
Senior Manager
Senior Manager
User avatar
P
Joined: 20 Mar 2018
Posts: 382
Location: Ghana
Concentration: Finance, Real Estate
Re: If 1/x-1/y=1/z, what is the value of y, in terms of x and z?  [#permalink]

Show Tags

New post 22 Feb 2019, 01:33
Asked y interms of x and z ,Therefore answer should be y= blah blah x blah blah z
1/x-1/y=1/z
Now let’s eliminate the denominators with the LCM (xyz)
( xyz)•1/(x) - (xyz)•1/y= (xyz)•1/z
yz - xz = xy
yz -xy = xz
y(z - x) = xz
y = xz/(z - x)

Answer is A

Posted from my mobile device
Senior Manager
Senior Manager
avatar
G
Joined: 04 Aug 2010
Posts: 477
Schools: Dartmouth College
Re: If 1/x-1/y=1/z, what is the value of y, in terms of x and z?  [#permalink]

Show Tags

New post 22 Feb 2019, 05:36
MathRevolution wrote:
[GMAT math practice question]

If \(\frac{1}{x}-\frac{1}{y}=\frac{1}{z}\), what is the value of \(y\), in terms of \(x\) and \(z\)?

\(A. \frac{xz}{(z-x)}\)
\(B. \frac{xz}{(x-z)}\)
\(C. \frac{x}{z(z-x)}\)
\(D. \frac{z}{x(x-z)}\)
\(E. xz(z-x)\)


Let \(x=1\) and \(y=\frac{3}{2}\), with the result that \(\frac{1}{z} = 1 - \frac{2}{3} = \frac{1}{3}\), so \(z=3\).

Since the question stem asks for the value of y, the correct answer must yield \(\frac{3}{2}\) when x=1 and z=3.
Since B and D include x-z and thus will yield a negative result, eliminate B and D.
Since E includes only multiplication and thus cannot yield \(\frac{3}{2}\), eliminate E.
Between A and C, only A yields \(\frac{3}{2}\):
\(\frac{xz}{z-x} = \frac{1*3}{3-1} = \frac{3}{2}\)


_________________
GMAT and GRE Tutor
Over 1800 followers
GMATGuruNY@gmail.com
New York, NY
If you find one of my posts helpful, please take a moment to click on the "Kudos" icon.
Available for tutoring in NYC and long-distance.
For more information, please email me at GMATGuruNY@gmail.com.
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 8033
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: If 1/x-1/y=1/z, what is the value of y, in terms of x and z?  [#permalink]

Show Tags

New post 24 Feb 2019, 07:00
=>
Making \(y\) the subject of the equation \(\frac{1}{x} – \frac{1}{y} = \frac{1}{z}\) yields \(\frac{1}{y} = \frac{1}{x} – \frac{1}{z} = \frac{(z-x)}{xz}\), and \(y = \frac{xz}{(z-x)}.\)

Therefore, the answer is A.
Answer: A
_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $79 for 1 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"
GMAT Club Bot
Re: If 1/x-1/y=1/z, what is the value of y, in terms of x and z?   [#permalink] 24 Feb 2019, 07:00
Display posts from previous: Sort by

If 1/x-1/y=1/z, what is the value of y, in terms of x and z?

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





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