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

 It is currently 20 Apr 2015, 22:42

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Are x and y both positive - GMATPrep

Author Message
TAGS:
Manager
Joined: 02 Aug 2007
Posts: 232
Schools: Life
Followers: 3

Kudos [?]: 33 [0], given: 0

Are x and y both positive - GMATPrep [#permalink]  18 Jan 2009, 18:26
Are x and y both positive?

1) 2x - 2y = 1
2) x/y > 1
Manager
Joined: 02 Aug 2007
Posts: 232
Schools: Life
Followers: 3

Kudos [?]: 33 [0], given: 0

Re: Are x and y both positive - GMATPrep [#permalink]  18 Jan 2009, 18:47
Intern
Joined: 09 Jan 2009
Posts: 10
Followers: 0

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

Re: Are x and y both positive - GMATPrep [#permalink]  18 Jan 2009, 18:59
Is it the correct answer ?
Intern
Joined: 09 Jan 2009
Posts: 10
Followers: 0

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

Re: Are x and y both positive - GMATPrep [#permalink]  18 Jan 2009, 19:07
Sorry...It looks like the correct answer is E.

Explanation :

x-y=1/2
x>y

Now lets say x=4.5 and y=4 ...this gives x-y=1/2 ...Here x and y are positive.

if we say x=-4 and y=-4.5 then x-y=1/2...Here both x and y are negative.

Isn't it ??

What was the answer in Gmat Prep ??
Manager
Joined: 02 Aug 2007
Posts: 232
Schools: Life
Followers: 3

Kudos [?]: 33 [0], given: 0

Re: Are x and y both positive - GMATPrep [#permalink]  18 Jan 2009, 19:23
vicky81 wrote:
Sorry...It looks like the correct answer is E.

Explanation :

x-y=1/2
x>y

Now lets say x=4.5 and y=4 ...this gives x-y=1/2 ...Here x and y are positive.

if we say x=-4 and y=-4.5 then x-y=1/2...Here both x and y are negative.

Isn't it ??

What was the answer in Gmat Prep ??

How do you get x>y? We don't know whether x or y are +ve or -ve, which can change the inequality sign.

OA is C
Senior Manager
Joined: 30 Nov 2008
Posts: 493
Schools: Fuqua
Followers: 10

Kudos [?]: 154 [0], given: 15

Re: Are x and y both positive - GMATPrep [#permalink]  18 Jan 2009, 19:56
x-ALI-x wrote:
Are x and y both positive?

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

IMO E

Stmt 1 : 2x - 2y = 1 ==> 2(x - y) = 1 ==> x - y = 1/2.

Here are examples for x and y satisfying Stmt 1 equation. hence cannot say whether X > 0 and Y > 0. Insufficent.

(x, y) = (+,+) ==> x = 1, y = 1/2
(x, y) = (+,-) ==> x = 1/2, y = -1
(x, y) = (-,+) ==> x = -1/2, y = 1
(x, y) = (-,-) ==> x = -1/4, y = -3/4

Stmt 2 : x/y > 1 ==> x > y.

Here are examples for x and y satisfying Stmt 2 equation. hence cannot say whether X > 0 and Y > 0. Insufficent.

(x, y) = (+,+) ==> x = 2, y = 1
(x, y) = (+,-) ==> x = 2, y = -1
(x, y) = (-,+) ==> not possible
(x, y) = (-,-) ==> x = -1, y = -2

Now consider both the stmt together. Here we can conclude that X > 0, but Y can be > 0 or not greater than 0. Hence insufficent.
SVP
Joined: 29 Aug 2007
Posts: 2497
Followers: 57

Kudos [?]: 554 [0], given: 19

Re: Are x and y both positive - GMATPrep [#permalink]  18 Jan 2009, 20:22
x-ALI-x wrote:
Are x and y both positive?

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

1: x - y = 1/2. insuff.

2: x/y > 1. both are either -ve or +ve. also insuff.

togather: lxl > lyl otherwise x/y cannot be > 1.

with that constraint, if x and y both are -ve, x - y cannot be 1/2.
if both are +ve, then only x - y = 1/2 possible. therefore suff.

Hence C.
_________________
SVP
Joined: 04 May 2006
Posts: 1936
Schools: CBS, Kellogg
Followers: 19

Kudos [?]: 430 [0], given: 1

Re: Are x and y both positive - GMATPrep [#permalink]  19 Jan 2009, 01:44
x-ALI-x wrote:
Are x and y both positive?

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

1) x=y+1/2 clearly not suff

2) is the same as:

(x-y)/y >0, so x and y have the same sign, not suff

1 and 2 suff:(x-y)/y = (1/2)/y >0, so y must be positive, x in turn must be positive also. because x and y have the same sign
_________________
Senior Manager
Joined: 23 May 2008
Posts: 428
Followers: 4

Kudos [?]: 124 [0], given: 14

Re: Are x and y both positive - GMATPrep [#permalink]  19 Jan 2009, 02:12
sondenso wrote:
x-ALI-x wrote:
Are x and y both positive?

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

1) x=y+1/2 clearly not suff

2) is the same as:

(x-y)/y >0, so x and y have the same sign, not suff

1 and 2 suff:(x-y)/y = (1/2)/y >0, so y must be positive, x in turn must be positive also. because x and y have the same sign

sondenso can u please explain the step no. 3 i.e combining both the statement 1+2.........
x-y)/y = (1/2)/y >0,

Manager
Joined: 04 Jan 2009
Posts: 243
Followers: 1

Kudos [?]: 9 [0], given: 0

Re: Are x and y both positive - GMATPrep [#permalink]  19 Jan 2009, 09:33
GMAT TIGER wrote:
x-ALI-x wrote:
Are x and y both positive?

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

1: x - y = 1/2. insuff.

2: x/y > 1. both are either -ve or +ve. also insuff.

togather: lxl > lyl otherwise x/y cannot be > 1.

with that constraint, if x and y both are -ve, x - y cannot be 1/2.
if both are +ve, then only x - y = 1/2 possible. therefore suff.

Hence C.

I understand your reasoning that both individually are insufficient.
Now,x>y and x=y+0.5
Are both integers? If not, y can be -0.25 and x can be 0.25 and still we satisfy both statements. Or y can be 1 and x will be 1.5. Thus, both together will not be sufficient.
_________________

-----------------------
tusharvk

SVP
Joined: 29 Aug 2007
Posts: 2497
Followers: 57

Kudos [?]: 554 [0], given: 19

Re: Are x and y both positive - GMATPrep [#permalink]  19 Jan 2009, 19:18
tusharvk wrote:
GMAT TIGER wrote:
x-ALI-x wrote:
Are x and y both positive?

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

1: x - y = 1/2. insuff.

2: x/y > 1. both are either -ve or +ve. also insuff.

togather: lxl > lyl otherwise x/y cannot be > 1.

with that constraint, if x and y both are -ve, x - y cannot be 1/2.
if both are +ve, then only x - y = 1/2 possible. therefore suff.

Hence C.

I understand your reasoning that both individually are insufficient.
Now,x>y and x=y+0.5
Are both integers? If not, y can be -0.25 and x can be 0.25 and still we satisfy both statements. Or y can be 1 and x will be 1.5. Thus, both together will not be sufficient.

if y can be -0.25 and x can be 0.25, do they satisfy (1) "x - y = 1/2" and (2) "x/y > 1"/
_________________
Intern
Joined: 19 Jan 2009
Posts: 17
Followers: 0

Kudos [?]: 1 [0], given: 0

Re: Are x and y both positive - GMATPrep [#permalink]  19 Jan 2009, 21:35
Are x and y both positive?

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

stmt 1: x - y = 1/2 which is insufficient

stmt 2; x/y > 1 which is insufficient

combined :

stmt 1 can be simplifed to x = y + 1/2

now plug in this in stmt 2

( y + 1/2) / y > 1

1 + 1/2y > 1

1/2y > 0
which implies y is positive so is x .

Manager
Joined: 04 Jan 2009
Posts: 243
Followers: 1

Kudos [?]: 9 [0], given: 0

Re: Are x and y both positive - GMATPrep [#permalink]  20 Jan 2009, 05:31
[/quote]
I understand your reasoning that both individually are insufficient.
Now,x>y and x=y+0.5
Are both integers? If not, y can be -0.25 and x can be 0.25 and still we satisfy both statements. Or y can be 1 and x will be 1.5. Thus, both together will not be sufficient.[/quote]

if y can be -0.25 and x can be 0.25, do they satisfy (1) "x - y = 1/2" and (2) "x/y > 1"/[/quote]

Yes. got my mistake. I multiplied both sides of x/y>1 by y without knowing if y is negative or positive.
_________________

-----------------------
tusharvk

SVP
Joined: 04 May 2006
Posts: 1936
Schools: CBS, Kellogg
Followers: 19

Kudos [?]: 430 [0], given: 1

Re: Are x and y both positive - GMATPrep [#permalink]  20 Jan 2009, 06:03
gurpreet07 wrote:
sondenso can u please explain the step no. 3

combined :

stmt 1 can be simplifed to x = y + 1/2

now plug in this in stmt 2

( y + 1/2) / y > 1

1 + 1/2y > 1

1/2y > 0
which implies y is positive so is x .

_________________
Re: Are x and y both positive - GMATPrep   [#permalink] 20 Jan 2009, 06:03
Similar topics Replies Last post
Similar
Topics:
1 Are x and y both positive? 7 29 Jan 2009, 05:21
are x and y both positive? 5 09 Jul 2007, 10:24
2 Are x and y both positive? 25 02 Oct 2006, 20:25
1 Are x and y both positive? 30 08 Jun 2006, 17:24
Are x and y both positive? 6 21 May 2006, 10:48
Display posts from previous: Sort by