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

It is currently 15 Dec 2019, 16:01

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

x = y - (50/y), where x and y are both > 0 If the value of y is doubl

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

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 59730
x = y - (50/y), where x and y are both > 0 If the value of y is doubl  [#permalink]

Show Tags

New post 14 May 2016, 03:54
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

65% (01:59) correct 35% (01:51) wrong based on 100 sessions

HideShow timer Statistics

Math Expert
avatar
V
Joined: 02 Aug 2009
Posts: 8326
Re: x = y - (50/y), where x and y are both > 0 If the value of y is doubl  [#permalink]

Show Tags

New post 14 May 2016, 08:20
Bunuel wrote:
x = y - (50/y), where x and y are both > 0. If the value of y is doubled in the equation above, the value of x will

A. decrease
B. stay the same
C. increase four fold
D. double
E. increase to more than double


hi,

lets see what will happen to each term..
the POSITIVE quantity, y, will double....
the NEGATIVE quantity 50/y will become LESSER as the denominator is doubled..

so OVERALL effect on x will be (DOUBLED positive - LESSER quantity), so x will increase MORE than double..
E

also --
x when y is doubled -
\(x_1= 2y - \frac{50}{2y} = \frac{2y^2-25}{y}\)......... (i)and
\(2x = 2( y-\frac{50}{y}) = \frac{2y^2-100}{y}\)...(ii)
clearly (i) > (ii)
so \(x_1>2x\)
_________________
Board of Directors
User avatar
D
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4834
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User
Re: x = y - (50/y), where x and y are both > 0 If the value of y is doubl  [#permalink]

Show Tags

New post 14 May 2016, 08:29
1
Bunuel wrote:
x = y - (50/y), where x and y are both > 0. If the value of y is doubled in the equation above, the value of x will

A. decrease
B. stay the same
C. increase four fold
D. double
E. increase to more than double


Alternate approach

Plug in some values of y > 0

Let y = 10

So, x = y - (50/y)

Or, x = 10 - (50/10) => 5

Quote:
If the value of y is doubled


Let y = 20

So, x = y - (50/y)

Or, x = 20 - (50/20) =>17.5

So, x increases from 5 to 17.5

Hence the number increases 3.5 times, thus the correct answer will be (E)
_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
Target Test Prep Representative
User avatar
V
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8701
Location: United States (CA)
Re: x = y - (50/y), where x and y are both > 0 If the value of y is doubl  [#permalink]

Show Tags

New post 04 Oct 2018, 19:33
Bunuel wrote:
x = y - (50/y), where x and y are both > 0. If the value of y is doubled in the equation above, the value of x will

A. decrease
B. stay the same
C. increase four fold
D. double
E. increase to more than double



We can let y = 10; then x = 10 - (50/10) = 5. Now, let’s the double the value of y to 20; now we have x = 20 - (50/20) = 17.5. We see that the value of x increases to more than double.

Answer: E
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

GMAT Club Bot
Re: x = y - (50/y), where x and y are both > 0 If the value of y is doubl   [#permalink] 04 Oct 2018, 19:33
Display posts from previous: Sort by

x = y - (50/y), where x and y are both > 0 If the value of y is doubl

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





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