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

It is currently 02 Sep 2015, 15:51
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

Two numbers are such that their sum is 54 and product is

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Senior Manager
Senior Manager
User avatar
Joined: 30 Aug 2003
Posts: 330
Location: BACARDIVILLE
Followers: 1

Kudos [?]: 4 [0], given: 0

Two numbers are such that their sum is 54 and product is [#permalink] New post 29 Jan 2004, 14:05
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Two numbers are such that their sum is 54 and product is 629. Find the difference of the numbers.

a. 20
b. 25
c. 40
d. 46
e. None of these
_________________

Pls include reasoning along with all answer posts.
****GMAT Loco****
Este examen me conduce jodiendo loco

Director
Director
avatar
Joined: 03 Jul 2003
Posts: 654
Followers: 2

Kudos [?]: 36 [0], given: 0

 [#permalink] New post 29 Jan 2004, 14:26
I got A ; 20 by plugging numbers
took alomost 10 mins to solve

Look simple but takes long time to solve.
Any easy methods to solve this question :?
Senior Manager
Senior Manager
User avatar
Joined: 30 Aug 2003
Posts: 330
Location: BACARDIVILLE
Followers: 1

Kudos [?]: 4 [0], given: 0

 [#permalink] New post 29 Jan 2004, 14:47
Kp, your answer is NOT in sync with the official answer.

My reasoning was this:
Right off the bat we can set up an equation. If we let the two numbers = x1, and x2.
x1 + x2 = 54.........(is a given)
x1 * x2 = 629 ....(is a given)
Hence, x1^2 - 54x1 + 629 = 0
Solve quadratic for x1....I got stuck here though...
_________________

Pls include reasoning along with all answer posts.
****GMAT Loco****
Este examen me conduce jodiendo loco

Manager
Manager
User avatar
Joined: 26 Dec 2003
Posts: 227
Location: India
Followers: 1

Kudos [?]: 2 [0], given: 0

 [#permalink] New post 29 Jan 2004, 15:13
a) 20, the factors of 629 are 17 and 37. So 17+37=54 and 17*37=629
Senior Manager
Senior Manager
User avatar
Joined: 30 Aug 2003
Posts: 330
Location: BACARDIVILLE
Followers: 1

Kudos [?]: 4 [0], given: 0

 [#permalink] New post 29 Jan 2004, 15:24
ofAns was (e)
But I guess you are right
nice
_________________

Pls include reasoning along with all answer posts.
****GMAT Loco****
Este examen me conduce jodiendo loco

Director
Director
avatar
Joined: 03 Jul 2003
Posts: 654
Followers: 2

Kudos [?]: 36 [0], given: 0

 [#permalink] New post 29 Jan 2004, 15:55
sunniboy007 wrote:
ofAns was (e)
But I guess you are right
nice


What is the source of the question?
Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2003
Posts: 325
Location: dallas , tx
Followers: 1

Kudos [?]: 11 [0], given: 0

 [#permalink] New post 29 Jan 2004, 17:02
one more method.. let the 1st number is x and 2nd number is 54-x
then their product is x*(54-x)=629..factorise..
_________________

shubhangi

SVP
SVP
User avatar
Joined: 30 Oct 2003
Posts: 1794
Location: NewJersey USA
Followers: 5

Kudos [?]: 48 [0], given: 0

 [#permalink] New post 29 Jan 2004, 20:29
Another method.

(a-b) ^2 = (a+b)^2-4ab
= 54^2-4*629 = 400
a-b = 20
Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2003
Posts: 325
Location: dallas , tx
Followers: 1

Kudos [?]: 11 [0], given: 0

 [#permalink] New post 30 Jan 2004, 07:30
hey Anand.. would u please tell me how did u get 4ab.. is'nt 2ab..
(a-b)^2= (a+b)^2-2ab..
or i've forgotten the formula..pl..tell me ..if am wrong..
_________________

shubhangi

Director
Director
User avatar
Joined: 28 Oct 2003
Posts: 503
Location: 55405
Followers: 1

Kudos [?]: 12 [0], given: 0

 [#permalink] New post 30 Jan 2004, 09:07
Numbers that make nine (via multiplication):
1 9
3 3
7 7

Of these, only 7 and 7 will sum to make 4.

We need to multiply to the 630 ballpark. sqrt 630 is about 25.

Take 27 and 27. No good.

17 and 37 should be the next thing to try.

To get a 51 in quant (and I did not get a 51 in quant), you probably need to be able to anser the question with a similar fast thought process.

Wasting 3 or 4 minutes on questions like this is a recipe for a low score.
SVP
SVP
User avatar
Joined: 30 Oct 2003
Posts: 1794
Location: NewJersey USA
Followers: 5

Kudos [?]: 48 [0], given: 0

 [#permalink] New post 30 Jan 2004, 10:25
Hi stoolfi,

You are scaring me man! If you didnt get 51 in Qauntitative test then I know what to expect.

Anand.

Hi Shubangi,

we know a+b and ab but we want to know a-b.

1. (a-b)^2 = a^2+b^2-2ab
2. (a+b)^2 = a^2+b^2+2ab

so from eq 1 a^2+b^2 = (a-b)^2+2ab
Substitute this in eq 2

(a+b)^2 = (a-b)^2+2ab+2ab
so (a-b)^2 = (a+b)^2-4ab
I hope it is clear.
  [#permalink] 30 Jan 2004, 10:25
Display posts from previous: Sort by

Two numbers are such that their sum is 54 and product is

  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®.