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

It is currently 15 Aug 2018, 09:45

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

GmatPrep PS Question

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
User avatar
Joined: 26 Jun 2007
Posts: 104
GmatPrep PS Question  [#permalink]

Show Tags

New post 02 Feb 2009, 11:46
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

HideShow timer Statistics

Is there a way to solve it less than 3 minutes?

OA will follow, please explain


** My apologies for not typing the question for future searches - don't you just hate all those signs? :wink: **

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

Attachments

GP.JPG
GP.JPG [ 49.53 KiB | Viewed 1377 times ]

SVP
SVP
User avatar
Joined: 07 Nov 2007
Posts: 1728
Location: New York
Re: GmatPrep PS Question  [#permalink]

Show Tags

New post 02 Feb 2009, 12:36
GGUY wrote:
Is there a way to solve it less than 3 minutes?

OA will follow, please explain


** My apologies for not typing the question for future searches - don't you just hate all those signs? :wink: **



assume x=y=1 you can eliminate option I and III right away.

To find Option III

\(1/sqrt{x+y}=sqrt{x+y}/{x+y}\)
option III = \(sqrt{x}+sqrt{y}/{x+y}\)

Need to find out \(sqrt{x}+sqrt{y} > sqrt{x+y}\)

-- > square on both sides
--> \(x+y+2*sqrt{xy} > x+y\)
this is always true
so Square root of these also true

Fortunately I could solve within 3 minutes.. but will see if this answer match with OA or not.

C
_________________

Your attitude determines your altitude
Smiling wins more friends than frowning

Intern
Intern
User avatar
Joined: 25 Jan 2009
Posts: 3
Re: GmatPrep PS Question  [#permalink]

Show Tags

New post 02 Feb 2009, 12:49
(1) rewrite \(\frac{1}{sqrt{x+y}}\) = \(\frac{1}{sqrt{x+y}}.\frac{sqrt{x+y}}{sqrt{x+y}}\)= \(\frac{sqrt{x+y}}{x+y}\)

(2) You do not know whether \(2x > x + y\) because \(y\) could be \(> x\) , so that leaves with II and III

(3) To test II and III check whether \(sqrt{x}+sqrt{y} > sqrt{x+y}\)

\(sqrt{x}+{sqrt{y} > {sqrt{x+y}\)
\((sqrt{x}+{sqrt{y})^2 > ({sqrt{x+y})^2\)
\(x+2{sqrt{xy} + y > x+y\)

So the left side is greater than the right side, which makes option II valid only (in option III the left side would be less than the right side)

I think doable in 2min, but hope it's right! :)

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: GmatPrep PS Question &nbs [#permalink] 02 Feb 2009, 12:49
Display posts from previous: Sort by

GmatPrep PS Question

  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®.