Find all School-related info fast with the new School-Specific MBA Forum

It is currently 07 Feb 2016, 00:33
GMAT Club Tests

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Pearson Vue CAT Quant PS-need help

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Intern
Intern
avatar
Joined: 19 Oct 2005
Posts: 12
Location: london
Followers: 0

Kudos [?]: 0 [0], given: 0

Pearson Vue CAT Quant PS-need help [#permalink] New post 01 Jan 2006, 03:13
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Hi all, I just took the first GMATPREP cat yesterday and am disappointed as they dont have explanations for your wrong answers. If any of you know how to solve this one it would really help. Thanks and Happy New Year!!!

If y and n are positive intergers and 450y=n^3 which of the following is an interger.
I. y/(3)(2^2)(5)

II. y/(3^2)(2)(5)

III. y/(3)(2)(5^2)

I simply cannot figure out what 450y=n^3 is. Any ideas??? Thank you.
Kaplan Promo CodeKnewton GMAT Discount CodesVeritas Prep GMAT Discount Codes
Director
Director
avatar
Joined: 17 Dec 2005
Posts: 548
Location: Germany
Followers: 1

Kudos [?]: 23 [0], given: 0

 [#permalink] New post 01 Jan 2006, 04:30
Before I'll explain it to you. Is II and III the solution?
Director
Director
avatar
Joined: 13 Nov 2003
Posts: 790
Location: BULGARIA
Followers: 1

Kudos [?]: 32 [0], given: 0

 [#permalink] New post 01 Jan 2006, 05:07
450=45x10=9x5x10=3^2x5^2x2xY=N^3 then Y should contain 3x5x2^2
Intern
Intern
avatar
Joined: 19 Oct 2005
Posts: 12
Location: london
Followers: 0

Kudos [?]: 0 [0], given: 0

 [#permalink] New post 01 Jan 2006, 05:56
Thanks BG, I only is the solution but I dont understand how you get to

Y should contain 3x5x2^2 from 3^2x5^2x2xY=N^3

Could you please explain if you have time. Many thanks.
Director
Director
avatar
Joined: 13 Nov 2003
Posts: 790
Location: BULGARIA
Followers: 1

Kudos [?]: 32 [0], given: 0

 [#permalink] New post 01 Jan 2006, 07:35
since 450y=n^3 and y and n are positive integers, 450y should contain third powers of all factors for n^3 to be an integer. You factor out 450, and see that it is 3^2x5^2x2 so you need Y to contain 2^2x3x5 as factors
hope it helps
Intern
Intern
avatar
Joined: 17 Jan 2006
Posts: 9
Followers: 0

Kudos [?]: 0 [0], given: 0

Here it goes... [#permalink] New post 25 Jan 2006, 06:05
Hi , I hope to address the problem in the following manner ::-

given :: 450y=n^3

=> n=third_root_of(450y)
=> n=third_root_of(5x3x3x5x2xy)

and also its given that n and y are integers ; so to get n as integer
we have to have , y, such that we can get the third root.

therefore, y should be 5x3x2x2

Once we have the value of y , simply substitute in given options to find out , which one leaves a integer value. And hence the option is (1)

Rgds,
Ak-
CEO
CEO
User avatar
Joined: 20 Nov 2005
Posts: 2910
Schools: Completed at SAID BUSINESS SCHOOL, OXFORD - Class of 2008
Followers: 20

Kudos [?]: 175 [0], given: 0

 [#permalink] New post 25 Jan 2006, 16:50
450 y = n^3 means 5^2 * 3^2 * 2 * y = n^3

So y must be multiple of 5* 3* 2^2

so y = A * 5* 3* 2^2 where A is a +ve integer.

Now put this value of y in I, II and III. Only I comes out be integer.
_________________

SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

  [#permalink] 25 Jan 2006, 16:50
Display posts from previous: Sort by

Pearson Vue CAT Quant PS-need help

  Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group and phpBB SEO

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®.