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

It is currently 28 Jul 2014, 03:00

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

Are x and y both positive? 1. 2x-2y = 1 2. x/y >1

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
SVP
SVP
User avatar
Joined: 05 Jul 2006
Posts: 1542
Followers: 5

Kudos [?]: 65 [0], given: 39

Are x and y both positive? 1. 2x-2y = 1 2. x/y >1 [#permalink] New post 07 Sep 2006, 01:59
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 1 sessions
Are x and y both positive?

1. 2x-2y = 1
2. x/y >1
Current Student
User avatar
Joined: 29 Jan 2005
Posts: 5253
Followers: 23

Kudos [?]: 120 [0], given: 0

GMAT Tests User Reviews Badge
 [#permalink] New post 07 Sep 2006, 04:04
C is the TRAP answer for the rushed, paniky test taker.

It's (E)

Gonna prove it now...

Statement 1: 2x-2y=1 ---> x-y=1/2 ---> x=y+1/2

If x>0 then y>-1/2 <or> if x<0 then y<-1/2 INSUFF

Statement 2: x/y>1 ---> x>y ---> x-y>0

If x>0 then y>0 <or> if x<0 then y<0 INSUFF

Together, if x>0 then y can be > 0 or -1/2 <or> if x<0 y can be <0 or -1/2 INSUFF

Answer is (E) :done

Bring it on yezz..

Last edited by GMATT73 on 07 Sep 2006, 05:33, edited 1 time in total.
Current Student
User avatar
Joined: 29 Jan 2005
Posts: 5253
Followers: 23

Kudos [?]: 120 [0], given: 0

GMAT Tests User Reviews Badge
 [#permalink] New post 07 Sep 2006, 05:15
haas_mba07 wrote:
I am with you until the S1 & S2 insufficient parts.

For S1 & S2,
if x>0, then y > {0, -1/2},

Wouldn't that violate x/y > 1?

If x = 1, y = 1/2 x/y = -2 ?

GMATT73 wrote:
Together, if x>0 then y can be > 0 or -1/2 <or> if x<0 y can be <0 or -1/2 INSUFF


Double checked my math Haas. The two statements combined leave a void between 0 and -1/2. This is why I am standing by (E)
VP
VP
User avatar
Joined: 02 Jun 2006
Posts: 1270
Followers: 2

Kudos [?]: 35 [0], given: 0

GMAT Tests User
 [#permalink] New post 07 Sep 2006, 05:17
Can you imply
x>y, when x/y > 1, though we don't know signs of x and y?

If x = -5, y = -1,
x/y > 1, but x < y.

What you need to say is |x| > |y|...?


GMATT73 wrote:
Statement 2: x/y>1 ---> x>y ---> x-y>0

S1 & S2:
Together, if x>0 then y can be > 0 or -1/2 <or> if x<0 y can be <0 or -1/2 INSUFF
VP
VP
User avatar
Joined: 21 Aug 2006
Posts: 1026
Followers: 1

Kudos [?]: 17 [0], given: 0

GMAT Tests User
 [#permalink] New post 07 Sep 2006, 05:56
I will go with C.

Here are my reasons:

We all agree that x and y can be either both positive or both negative. If we substitute both negative numbers in 2x-2y=1, then those same values dont hold good in case of x/y>1. If we substitute both positive numbers in 2x-2y=1, then those same values hold good in case of x/y>1. So I say that x and y are positive values.

Do correct me if I am wrong. :-D
_________________

The path is long, but self-surrender makes it short;
the way is difficult, but perfect trust makes it easy.

VP
VP
User avatar
Joined: 02 Jun 2006
Posts: 1270
Followers: 2

Kudos [?]: 35 [0], given: 0

GMAT Tests User
 [#permalink] New post 07 Sep 2006, 06:00
I second that... C for me too.
Both x and y have to be both +ve or -ve.
Plugging in for S1 & S2 satisfies only one condition.

Good questions yezz... keep them coming.

ak_idc wrote:
I will go with C.

Here are my reasons:

We all agree that x and y can be either both positive or both negative. If we substitute both negative numbers in 2x-2y=1, then those same values dont hold good in case of x/y>1. If we substitute both positive numbers in 2x-2y=1, then those same values hold good in case of x/y>1. So I say that x and y are positive values.

Do correct me if I am wrong. :-D
Current Student
User avatar
Joined: 29 Jan 2005
Posts: 5253
Followers: 23

Kudos [?]: 120 [0], given: 0

GMAT Tests User Reviews Badge
 [#permalink] New post 07 Sep 2006, 06:39
haas_mba07 wrote:
I second that... C for me too.
Both x and y have to be both +ve or -ve.
Plugging in for S1 & S2 satisfies only one condition.

Good questions yezz... keep them coming.

ak_idc wrote:
I will go with C.

Here are my reasons:

We all agree that x and y can be either both positive or both negative. If we substitute both negative numbers in 2x-2y=1, then those same values dont hold good in case of x/y>1. If we substitute both positive numbers in 2x-2y=1, then those same values hold good in case of x/y>1. So I say that x and y are positive values.

Do correct me if I am wrong. :-D


Hey guys, can't both x and y be negative too? Now what's the answer???
VP
VP
User avatar
Joined: 21 Aug 2006
Posts: 1026
Followers: 1

Kudos [?]: 17 [0], given: 0

GMAT Tests User
 [#permalink] New post 07 Sep 2006, 06:44
If we take both negative, then we can't satisfy the second condition. That means effectively we are not using the information in second condition. If we take both positive, we are fullfiling the second condition and also we can solve the problem. Hence, I say C.. :)
_________________

The path is long, but self-surrender makes it short;
the way is difficult, but perfect trust makes it easy.

CEO
CEO
User avatar
Joined: 20 Nov 2005
Posts: 2922
Schools: Completed at SAID BUSINESS SCHOOL, OXFORD - Class of 2008
Followers: 13

Kudos [?]: 75 [0], given: 0

GMAT Tests User
 [#permalink] New post 07 Sep 2006, 07:08
C

St1: x-y = 1/2 : Clearly INSUFF

St2: x/y > 1: Clearly INSUFF

Together:
From St2 we can say that either both x and y are +ve or both are -ve.

If both +ve then x>y and st1 will also be satisfied.
If both -ve then y>x then lets take out the -ve sign of both x and y. Then st1 becomes x-y = -1/2 and st2 becomes x>y and its impossible.
So both x and y are +ve.
_________________

SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

Intern
Intern
User avatar
Joined: 06 Jan 2006
Posts: 13
Followers: 0

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

 [#permalink] New post 07 Sep 2006, 07:20
I go with E

from 1) x-y=1/2

insuff cause 3.5-3=0.5 (-->x,y positive) and -3+3.5=0.5 (-->x,y negative)

from 2) x>y

insuff

but in both exemples above x>y while x,y either positive or negative

thus 1) + 2) insuff.
SVP
SVP
User avatar
Joined: 05 Jul 2006
Posts: 1542
Followers: 5

Kudos [?]: 65 [0], given: 39

 [#permalink] New post 07 Sep 2006, 09:03
Are x and y both positive?

1. 2x-2y = 1
2. x/y >1

From one x-y = 1/2 this could be possible in three ways

1) x,y could be positive

2) x +ve and y -ve both fractions with absolute value less than 1/2

3) x,y are both -ve and y<x

thus insuff

from two

x/y > 1 they could be both positive x>y

or both -ve and y>x

thus not suff

both together


x/y >1 could be expressed as x-y/y>0 ie (1/2)/y>0

thus y is +ve AND SINCE X/Y> 1 thus x is positive and answer is C

OA is C

Last edited by yezz on 07 Sep 2006, 23:36, edited 2 times in total.
Intern
Intern
avatar
Joined: 02 Aug 2006
Posts: 23
Location: NYC
Followers: 0

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

 [#permalink] New post 07 Sep 2006, 16:11
Insider wrote:
I go with E

from 1) x-y=1/2

insuff cause 3.5-3=0.5 (-->x,y positive) and -3+3.5=0.5 (-->x,y negative)

from 2) x>y

insuff

but in both exemples above x>y while x,y either positive or negative

thus 1) + 2) insuff.


Insider, if x=-3 and y=-3.5, the first statement is fulfilled, but the second isn't: (-3/-3.5)<1.
Director
Director
User avatar
Joined: 28 Dec 2005
Posts: 761
Followers: 1

Kudos [?]: 8 [0], given: 0

GMAT Tests User
 [#permalink] New post 09 Sep 2006, 22:13
The answer is C.

The trick here is that

x/y > 1 does not simply mean that x > y.....MEMORIZE THIS.

it means :

1. x and y have the same sign
2. if x,y are +ve then x > y.
3. if x,y are -ve then x < y

Excellent problem...I was stumped for a bit.
GMAT Instructor
avatar
Joined: 04 Jul 2006
Posts: 1270
Location: Madrid
Followers: 23

Kudos [?]: 113 [0], given: 0

Re: A v.good iniquality DS(Dahiya post) [#permalink] New post 11 Sep 2006, 01:57
yezz wrote:
Are x and y both positive?

1. 2x-2y = 1
2. x/y >1


(1) y=x+1/2 NOT SUFF

(2) x and y have the same sign and x is further from 0 than is y (i.e |x|>|y|) NOT SUFF

Together, if x>y from (1) and |x|>|y| from (2), it follows than x>0 and thus (from (2)) y>0 SUFF

C
Senior Manager
Senior Manager
avatar
Joined: 15 Aug 2004
Posts: 329
Followers: 1

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

GMAT Tests User
 [#permalink] New post 12 Sep 2006, 02:50
Futuristic wrote:
2. if x,y are +ve then x > y.


Doesn't you second choice mean that the answer should be B...

It cannot be one +ve and one -ve or vice versa...
I cannot be both -ve, so only both +ve is left...
Director
Director
User avatar
Joined: 07 Jun 2004
Posts: 618
Location: PA
Followers: 2

Kudos [?]: 138 [0], given: 22

GMAT Tests User
 [#permalink] New post 13 Sep 2006, 10:55
I wud go with B on this one

the Q is is x & y both +ve


from II we see x / y > 1 or x > y

for x/y > +1 either both have to be -ve or both + ve

if we take both -ve then we cannot get x / y > 1 it will be always be < 1

eg: - 10 / -15 as -10 > -15 = .667 for this value to be > 1 and both x and y to be -ve then x < y eg : -10 / -5 = 2

so we are left with if x/y > 1 then both x and y are positive
Senior Manager
Senior Manager
User avatar
Joined: 07 Jul 2005
Posts: 406
Location: Sunnyvale, CA
Followers: 2

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

GMAT Tests User
 [#permalink] New post 14 Sep 2006, 12:11
(C).
As explained by Dahiya.

Combining both,
I says that x > y, and II says that either {x, y} are +ve or -ve
If {x, y} are -ve, then we cannot have x >y and x/y >1
Hence both x, y have to be +ve.
SVP
SVP
User avatar
Joined: 03 Jan 2005
Posts: 2255
Followers: 12

Kudos [?]: 189 [0], given: 0

GMAT Tests User
Re: A v.good iniquality DS(Dahiya post) [#permalink] New post 13 Oct 2006, 07:01
yezz wrote:
Are x and y both positive?

1. 2x-2y = 1
2. x/y >1


Sorry to drag this thread out of its grave. I thought it's a good chance to advocate my way of solving thing algebrally.

Here's what I'd do for 1 and 2 combined:

1=> 2x=1+2y, or x=(1+2y)/2
2=> x/y>1 meaning (1+2y)/2y>1
rephrase: 1/2y+1>1 => 1/2y>0
Therefore y>0
x=(1+2y)/2>0

Solving in this fashion sometimes can help to avoid the sign confusions that may accompany inequalities.
_________________

Keep on asking, and it will be given you;
keep on seeking, and you will find;
keep on knocking, and it will be opened to you.

Manager
Manager
User avatar
Joined: 08 Jul 2006
Posts: 90
Followers: 1

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

 [#permalink] New post 13 Oct 2006, 16:40
Picked C too. (Developing a new strategy for approaching tricky DS problems)

Making Statement 1 true by quickly picking numbers.
We can have 2(3) - 2(5/2) = 1 OR 2(-3) - 2(-7/2) = 1
x and y can be either both positive or both negative. INSUFF

From Statement 2, we only know x>y. INSUFF

Together,
If X>Y, then, in order for 2x - 2y = 1, both a and y must be positive.

C should suffice.
Senior Manager
Senior Manager
User avatar
Joined: 11 Jul 2006
Posts: 385
Location: TX
Followers: 1

Kudos [?]: 6 [0], given: 0

GMAT Tests User
Re: A v.good iniquality DS(Dahiya post) [#permalink] New post 14 Oct 2006, 22:28
HongHu wrote:
yezz wrote:
Are x and y both positive?

1. 2x-2y = 1
2. x/y >1


Sorry to drag this thread out of its grave. I thought it's a good chance to advocate my way of solving thing algebrally.

Here's what I'd do for 1 and 2 combined:

1=> 2x=1+2y, or x=(1+2y)/2
2=> x/y>1 meaning (1+2y)/2y>1
rephrase: 1/2y+1>1 => 1/2y>0
Therefore y>0
x=(1+2y)/2>0

Solving in this fashion sometimes can help to avoid the sign confusions that may accompany inequalities.


Excellent approach Honghu . it makes it much simpler and saves time.
Re: A v.good iniquality DS(Dahiya post)   [#permalink] 14 Oct 2006, 22:28
    Similar topics Author Replies Last post
Similar
Topics:
x and y are both positive? (1) 2x-2y = 1 (2) x/y > 1 meaningful 5 15 Feb 2009, 01:23
Are x and y both positive? (1) 2x - 2y = 1 (2) x/y > 1 Summer3 10 24 Mar 2007, 19:33
Are x and y both positive? 1) 2x -2y = 1 2) x/y > 1 I uvs_mba 8 22 Oct 2006, 21:10
Are x and y both positive? 1. 2x-2y = 1 2. x/y >1 ps_dahiya 9 30 Jul 2006, 20:03
1 Are x and y both positive? 1. 2x -2y = 1 2. x/y > 1 willget800 2 16 Apr 2006, 09:30
Display posts from previous: Sort by

Are x and y both positive? 1. 2x-2y = 1 2. x/y >1

  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®.