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

It is currently 16 Aug 2018, 06:48

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 the function Q is defined by the formula Q = 5w/(4x(z^2))

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

Hide Tags

Intern
Intern
avatar
Joined: 02 Mar 2012
Posts: 8
If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post Updated on: 21 Apr 2012, 00:11
14
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

74% (01:25) correct 26% (01:52) wrong based on 480 sessions

HideShow timer Statistics

If the function Q is defined by the formula Q = 5w/(4x(z^2)), by what factor will Q be multiplied if w is quadrupled, x is doubled, and z is tripled?

A. 1/9
B. 2/9
C. 4/9
D. 3/9
E. 2/27

Originally posted by gmattest27 on 20 Apr 2012, 20:05.
Last edited by Bunuel on 21 Apr 2012, 00:11, edited 1 time in total.
Edited the question and added the OA
Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47924
Re: Inequalities  [#permalink]

Show Tags

New post 21 Apr 2012, 00:10
6
3
gmattest27 wrote:
If the function Q is defined by the formula Q = 5w/4xz^2 , by what factor will Q be multi-plied if w is quadrupled, x is doubled, and z is tripled?

Please help explain this ..

Thanks in advance


If the function Q is defined by the formula Q = 5w/(4x(z^2)), by what factor will Q be multiplied if w is quadrupled, x is doubled, and z is tripled?
A. 1/9
B. 2/9
C. 4/9
D. 3/9
E. 2/27

Given: \(Q=\frac{5w}{4x*z^2}\).

Now, quadruple \(w\), so make it \(4w\); double \(x\) so make it \(2x\); triple \(z\) and substitute these values instead of \(x\), \(y\), and \(z\) in the original equation:

\(\frac{5(4w)}{4(2x)*(3z)^2}=\frac{4*5w}{4*2x*9*z^2}=\frac{4*5w}{18*(4x*z^2)}=\frac{4}{18}*\frac{5w}{4x*z^2}=\frac{2}{9}*\frac{5w}{4x*z^2}\). Thus Q is multiplied by \(\frac{2}{9}\).

Answer: B.

Else plug-in values for \(x\), \(y\), and \(z\). Let \(x=y=z=1\) --> \(Q=\frac{5w}{4x*z^2}=\frac{5}{4}\).

\(4w=4\), \(2x=2\) and \(3z=3\) --> \(\frac{5*4}{4*2*3^2}=\frac{4}{18}*\frac{5}{4}=\frac{2}{9}*\frac{5}{4}\). Thus Q is multiplied by \(\frac{2}{9}\).

Answer: B.

Hope it's clear.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

General Discussion
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47924
Re: If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post 21 Jun 2013, 03:48
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

*New project from GMAT Club!!! Check HERE

All DS Functions and Custom Characters questions: search.php?search_id=tag&tag_id=40
All PS Functions and Custom Characters questions: search.php?search_id=tag&tag_id=61

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

Intern
Intern
avatar
Joined: 22 May 2013
Posts: 46
Concentration: General Management, Technology
GPA: 3.9
WE: Information Technology (Computer Software)
GMAT ToolKit User
Re: If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post 22 Jun 2013, 01:53
1
gmattest27 wrote:
If the function Q is defined by the formula Q = 5w/(4x(z^2)), by what factor will Q be multiplied if w is quadrupled, x is doubled, and z is tripled?

A. 1/9
B. 2/9
C. 4/9
D. 3/9
E. 2/27


We just need to find the factor thats all,

w -> quadrupled -> 4w
x-> doubled -> 2x
z-> tripled -> 3Z
Hence, Z^2 = 9Z^2

W is in numerator, and x*z in denominator.

Hence,
Additional factor being introduced = 4/2*9

=4/18 = 2/9 = B
_________________

PS: Like my approach? Please Help me with some Kudos. :-)

Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8187
Location: Pune, India
Re: If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post 16 Jul 2014, 23:06
gmattest27 wrote:
If the function Q is defined by the formula Q = 5w/(4x(z^2)), by what factor will Q be multiplied if w is quadrupled, x is doubled, and z is tripled?

A. 1/9
B. 2/9
C. 4/9
D. 3/9
E. 2/27


This is a very simple case of joint variation. Check out this link for a discussion on joint variation: http://www.veritasprep.com/blog/2013/02 ... g-jointly/
_________________

Karishma
Veritas Prep GMAT Instructor

Save up to $1,000 on GMAT prep through 8/20! Learn more here >

GMAT self-study has never been more personalized or more fun. Try ORION Free!

SVP
SVP
User avatar
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1835
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post 16 Jul 2014, 23:54
w becomes 4w ......... Resultant = 4

x becomes 2x ............ Resultant = 2

z becomes 3z ............. Resultant \(= 3^2 = 9\) (As z is sitting under a square sign)

Multiplication factor = \(\frac{4}{2*9} = \frac{2}{9}\)

Answer = B
_________________

Kindly press "+1 Kudos" to appreciate :)

Senior Manager
Senior Manager
User avatar
S
Joined: 25 Mar 2013
Posts: 264
Location: United States
Concentration: Entrepreneurship, Marketing
GPA: 3.5
GMAT ToolKit User Reviews Badge
Re: If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post 09 Jan 2017, 15:53
Just understand words Quadrupled = 4 times
Q = \(\frac{5w}{4x z^{2}}\)
\(\frac{5 x 4w}{4(2x) . (3z)^{2}}\)
Take out Q factor
\(\frac{4}{18}\)
\(\frac{2}{9}\)
B
_________________

I welcome analysis on my posts and kudo +1 if helpful. It helps me to improve my craft.Thank you

Director
Director
avatar
S
Joined: 12 Nov 2016
Posts: 772
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
GPA: 2.66
Re: If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post 20 Feb 2017, 19:09
I don't understand how Bunuel gets 18 in the denominator in the third step.
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47924
Re: If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post 20 Feb 2017, 23:59
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 7720
Premium Member
Re: If the function Q is defined by the formula Q = 5w/(4x(z^2))  [#permalink]

Show Tags

New post 15 Apr 2018, 19:13
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Re: If the function Q is defined by the formula Q = 5w/(4x(z^2)) &nbs [#permalink] 15 Apr 2018, 19:13
Display posts from previous: Sort by

If the function Q is defined by the formula Q = 5w/(4x(z^2))

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

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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

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®.