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

It is currently 21 Oct 2014, 13:58

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

PS natural number

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
SVP
SVP
User avatar
Joined: 07 Nov 2007
Posts: 1829
Location: New York
Followers: 27

Kudos [?]: 472 [0], given: 5

PS natural number [#permalink] New post 12 Feb 2009, 13:05
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
A natural number is divided into two positive unequal parts such that the ratio of the original number to the larger (divided) part is equal to the ratio of the larger part to the smaller part. What is the value of this ratio?

A (5^1/2 − 1)

B (5^1/2 + 1) / 2

C (5^1/2 + 1) / 4

D (5^1/2 + 1) / (5^1/2 − 1)

E (5^1/2 + 3) / (5^1/2 − 1)
_________________

Your attitude determines your altitude
Smiling wins more friends than frowning

Expert Post
CEO
CEO
User avatar
Joined: 17 Nov 2007
Posts: 3571
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 367

Kudos [?]: 1849 [0], given: 358

GMAT ToolKit User Premium Member
Re: PS natural number [#permalink] New post 12 Feb 2009, 13:17
Expert's post
B

n - a natural number
x - larger part
y - smaller part

n/x=x/y=a --> (x+y)/x=x/y=a --> 1+y/x=x/y=a ---> 1+1/a=a

a^2-a-1=0

a=\frac{1\pm\sqrt{5}}{2}

We have two positive parts, so a is positive: a=\frac{1+\sqrt{5}}{2}
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

SVP
SVP
User avatar
Joined: 07 Nov 2007
Posts: 1829
Location: New York
Followers: 27

Kudos [?]: 472 [0], given: 5

Re: PS natural number [#permalink] New post 12 Feb 2009, 14:01
walker wrote:
B

n - a natural number
x - larger part
y - smaller part

n/x=x/y=a --> (x+y)/x=x/y=a --> 1+y/x=x/y=a ---> 1+1/a=a

a^2-a-1=0

a=\frac{1\pm\sqrt{5}}{2}

We have two positive parts, so a is positive: a=\frac{1+\sqrt{5}}{2}


I arrived till a^2-a-1=0

I forgot how to solve the this quadratic equation... Do you need to remember the formula..
or easy way to find "a" from the equation ?
_________________

Your attitude determines your altitude
Smiling wins more friends than frowning

Expert Post
CEO
CEO
User avatar
Joined: 17 Nov 2007
Posts: 3571
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 367

Kudos [?]: 1849 [0], given: 358

GMAT ToolKit User Premium Member
Re: PS natural number [#permalink] New post 12 Feb 2009, 14:30
Expert's post
I think we need to remember it.
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Re: PS natural number   [#permalink] 12 Feb 2009, 14:30
    Similar topics Author Replies Last post
Similar
Topics:
PS numbers carollu 2 09 May 2011, 05:51
PS -Numbers ALD 2 08 Jan 2009, 10:17
PS-Numbers vivektripathi 3 07 Dec 2008, 06:33
PS-numbers LM 4 24 Jun 2007, 20:02
PS NUMBER mandy 1 09 Jun 2005, 01:33
Display posts from previous: Sort by

PS natural number

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| 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®.