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

It is currently 22 Aug 2014, 23:30

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

Is (y-10)^2 > (x+10)^2?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
Intern
Intern
avatar
Joined: 06 Sep 2012
Posts: 42
Concentration: Social Entrepreneurship
Followers: 0

Kudos [?]: 11 [1] , given: 42

Is (y-10)^2 > (x+10)^2? [#permalink] New post 15 Dec 2012, 10:31
1
This post received
KUDOS
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

43% (03:02) correct 57% (02:37) wrong based on 90 sessions
Is (y-10)^2 > (x+10)^2?

(1) -y > x+5
(2) x > y
[Reveal] Spoiler: OA

_________________

Life begins at the edge of your comfort zone.

Appreciate the +1!

1 KUDOS received
Moderator
Moderator
User avatar
Joined: 25 Apr 2012
Posts: 611
Location: India
GPA: 3.21
WE: Business Development (Other)
Followers: 13

Kudos [?]: 267 [1] , given: 650

Premium Member CAT Tests
Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 16 Dec 2012, 23:34
1
This post received
KUDOS
JJ2014 wrote:
Is (y-10)^2 > (x+10)^2?

(1) -y > x+5
(2) x > y



Hi JJ2014,

1. From St 1 , we get x+y<-5

X=10
Y= -4
Then St under consideration is not true i.e (y-10)^2> (x+10)^2

X=-11
y= 5

Then st under consideration is true

So A and D ruled out.

St 2 alone is not sufficient.

Ex X=3, y=2, St not true
X=-2, y=-3, St is true

So B ruled out.

Combining both the statements we get

x+y<-5 and x>y
We see that y<0 as otherwise if y>0 then the eqn X>y is not true.
Hence ans C
_________________


“If you can't fly then run, if you can't run then walk, if you can't walk then crawl, but whatever you do you have to keep moving forward.”


Last edited by WoundedTiger on 02 Jan 2014, 00:19, edited 1 time in total.
Manager
Manager
User avatar
Joined: 24 Mar 2010
Posts: 81
Followers: 0

Kudos [?]: 18 [0], given: 134

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 21 Dec 2012, 01:34
Karishma / Bunuel,

Could you throw some light on the below query.

I always have trouble in questions like this as to what numbers to pick. I end up going way beyond 3 minutes.

Do tell me the certain set of numbers/range of numbers that one should always begin testing with


P.S. I know it could vary from question to question but want a general set.
_________________

- Stay Hungry, stay Foolish -

Intern
Intern
avatar
Joined: 25 Mar 2012
Posts: 23
Location: India
Concentration: Strategy, General Management
GMAT 1: 710 Q50 V36
GPA: 3.04
WE: Consulting (Computer Software)
Followers: 0

Kudos [?]: 8 [0], given: 1

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 22 Dec 2012, 05:23
we need to find if (y-10)^2 > (x+10)^2?
or, is y^2 - 20y + 100 > x^2 + 20x + 100?
or, is y^2 - 20y > x^2 + 20x?
or, is y^2 - x^2 > 20(x + y)?
or, is (y+x)(y-x) > 20(x+y)?
here, because of inequality, we cannot divide by (x+y) on both sides, as we don't know whether (x+y) is positive or negative. But we can break this in 2:

(1). if (x+y) is +ve, is (y-x) > 20?
(2). if (x+y) is -ve, is (y-x) < 20?

Let's see the 1st option:

-y > x+5
or, x+y < -5
or, x+y is -ve
So, eq (2) needs to be proved. is (y-x) < 20? Can't say. This does not prove eq (2).

Let's see the 2nd option:

x > y
or, x-y > 0
or y-x < 0

So, irrespective of whether (x+y) is +ve or -ve, (y-x) is less than 0. So, the inequality can be answered by this statement alone. The answer should be B. I am not sure why the spoiler says C as the answer.
Intern
Intern
avatar
Joined: 07 Jul 2012
Posts: 10
Concentration: Finance
GMAT Date: 04-30-2014
Followers: 0

Kudos [?]: 3 [0], given: 0

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 27 Dec 2012, 05:27
anandrajakrishnan wrote:
we need to find if (y-10)^2 > (x+10)^2?
or, is y^2 - 20y + 100 > x^2 + 20x + 100?
or, is y^2 - 20y > x^2 + 20x?
or, is y^2 - x^2 > 20(x + y)?
or, is (y+x)(y-x) > 20(x+y)?
here, because of inequality, we cannot divide by (x+y) on both sides, as we don't know whether (x+y) is positive or negative. But we can break this in 2:

(1). if (x+y) is +ve, is (y-x) > 20?
(2). if (x+y) is -ve, is (y-x) < 20?

Let's see the 1st option:

-y > x+5
or, x+y < -5
or, x+y is -ve
So, eq (2) needs to be proved. is (y-x) < 20? Can't say. This does not prove eq (2).

Let's see the 2nd option:

x > y
or, x-y > 0
or y-x < 0

So, irrespective of whether (x+y) is +ve or -ve, (y-x) is less than 0. So, the inequality can be answered by this statement alone. The answer should be B. I am not sure why the spoiler says C as the answer.



hey Anand
Had a small question
when x > y we get y - x < 0
How can y - x < 0 by itself be sufficient to solve (y+x)(y-x) > 20(x+y) ?
I feel C is the correct answer .. we need both A and B to determine. Please clarify
1 KUDOS received
Intern
Intern
avatar
Joined: 25 Mar 2012
Posts: 23
Location: India
Concentration: Strategy, General Management
GMAT 1: 710 Q50 V36
GPA: 3.04
WE: Consulting (Computer Software)
Followers: 0

Kudos [?]: 8 [1] , given: 1

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 27 Dec 2012, 18:40
1
This post received
KUDOS
Adityam wrote:
anandrajakrishnan wrote:
we need to find if (y-10)^2 > (x+10)^2?
or, is y^2 - 20y + 100 > x^2 + 20x + 100?
or, is y^2 - 20y > x^2 + 20x?
or, is y^2 - x^2 > 20(x + y)?
or, is (y+x)(y-x) > 20(x+y)?
here, because of inequality, we cannot divide by (x+y) on both sides, as we don't know whether (x+y) is positive or negative. But we can break this in 2:

(1). if (x+y) is +ve, is (y-x) > 20?
(2). if (x+y) is -ve, is (y-x) < 20?

Let's see the 1st option:

-y > x+5
or, x+y < -5
or, x+y is -ve
So, eq (2) needs to be proved. is (y-x) < 20? Can't say. This does not prove eq (2).

Let's see the 2nd option:

x > y
or, x-y > 0
or y-x < 0

So, irrespective of whether (x+y) is +ve or -ve, (y-x) is less than 0. So, the inequality can be answered by this statement alone. The answer should be B. I am not sure why the spoiler says C as the answer.



hey Anand
Had a small question
when x > y we get y - x < 0
How can y - x < 0 by itself be sufficient to solve (y+x)(y-x) > 20(x+y) ?
I feel C is the correct answer .. we need both A and B to determine. Please clarify



Hmm. I need some retrospection here:

As I mentioned that the inequality can be divided in 2:

(1). if (x+y) is +ve, is (y-x) > 20?
(2). if (x+y) is -ve, is (y-x) < 20?

With the 2nd option, we get y-x < 0.
This doesn't resolve the inequality as we still need to prove which side of zero does (x+y) lies. So, 1st part is necessary.
Option C is the right choice. Thanks for clarifying.
Manager
Manager
avatar
Joined: 28 Dec 2012
Posts: 50
Schools: LBS '14
Followers: 1

Kudos [?]: 15 [0], given: 55

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 13 Jan 2013, 22:39
C.
Individually each one is insuffient by plugging values.

Now question stem:

Is (y-10)^2 > (x+10)^2?

= Is (y+x)(y-x-20) > 0 on simplification

1. gives (y+x)<-5 => (y+x) is negative.

Using 1, therefore the stem becomes Is (y-x-20) < 0 ?

or Is (y-x) < 20 ?

On using 2. if x >y => (y-x) is negative and hence (y-x) < 20 and the answer to the

stem is Yes. (combining 1. & 2.) Hence C.

KUDOS... If YOU LIKE IT :)
SVP
SVP
User avatar
Joined: 06 Sep 2013
Posts: 1627
Location: United States
Concentration: Finance
GMAT 1: 710 Q48 V39
WE: Corporate Finance (Investment Banking)
Followers: 11

Kudos [?]: 152 [0], given: 254

GMAT ToolKit User
Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 01 Jan 2014, 07:41
eaakbari wrote:
Karishma / Bunuel,

Could you throw some light on the below query.

I always have trouble in questions like this as to what numbers to pick. I end up going way beyond 3 minutes.

Do tell me the certain set of numbers/range of numbers that one should always begin testing with


P.S. I know it could vary from question to question but want a general set.


Karisha/Bunuel and other math experts

Would you please me so kind to advice on best approach for this question. I've been trying to grind it for several minutes but still unable to find an elegant way

Cheers!
J :)
3 KUDOS received
Senior Manager
Senior Manager
avatar
Status: Student
Joined: 26 Aug 2013
Posts: 261
Location: France
Concentration: Finance, General Management
GMAT 1: 650 Q47 V32
GPA: 3.44
Followers: 2

Kudos [?]: 28 [3] , given: 397

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 01 Jan 2014, 10:35
3
This post received
KUDOS
JJ2014 wrote:
Is (y-10)^2 > (x+10)^2?

(1) -y > x+5
(2) x > y


Hi,

I answered using the following process:

If (y-10)^2 > (x+10)^2 is true, then the difference between the two Y and X needs to be over 10 (Example: Y=-6 and X=5)

With 1) We have the beginning of the information

If -y > x+5 then it will be true for some numbers BUT, if Y=-5 and X=-100) Then you will have (-15)^2 > (-90)^2 which is impossible. You need X>Y

With 2) Used alone, the statement is not correct. If Y=10 and X=10255 than the equation (y-10)^2 > (x+10)^2 is false.
if you select other numbers than the equation will be right.

Then you comfirm the statement one with statement two.

Answer C

Hope it helps!
_________________

Think outside the box

Moderator
Moderator
User avatar
Joined: 25 Apr 2012
Posts: 611
Location: India
GPA: 3.21
WE: Business Development (Other)
Followers: 13

Kudos [?]: 267 [0], given: 650

Premium Member CAT Tests
Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 02 Jan 2014, 00:34
JJ2014 wrote:
Is (y-10)^2 > (x+10)^2?

(1) -y > x+5
(2) x > y



Here is another method I could throw in....We can simplify the given equation and we get

y^2 -20y>x^2-20x ------->y^2-x^2 -20 (y-x)>0
Taking (y-x) common we get -------> y-x (y+x -20)>0 -----> Eq 1
Now the Eq 1 will hold true if we have one of the 2 conditions satisfied ie.

y>x and y+x>20----------->Condition 1
or
y<x and (y+x)< 20 ---------->Condition 2


Now from St 1 we have that x+y<-5 -----This meets partially our condition 2 but we don't know whether x>y ( so A and D Ruled out ) so statement alone is not sufficient

From St 2, we have that x>y------> This statement also partially meets our condition2 but we don't know whether y+x<20 (So B ruled out ) so statement alone is not sufficient

Combining both the equations we get x>y and x+y<20 (because x+y<-5 and hence less than 20) and hence Equation 1 is true.

Ans C
_________________


“If you can't fly then run, if you can't run then walk, if you can't walk then crawl, but whatever you do you have to keep moving forward.”

Manager
Manager
avatar
Joined: 05 Nov 2012
Posts: 147
Followers: 1

Kudos [?]: 7 [0], given: 56

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 02 Jan 2014, 09:30
JJ2014 wrote:
Is (y-10)^2 > (x+10)^2?

(1) -y > x+5
(2) x > y

here is my solution:

(1) Not sufficient - examples were mentioned above
(2) Not sufficient - y can be large negative value and x can be small positive value or y can be small positive/negative value and x can be large positive value

(1) + (2)

Inequalities with the same sign can be added

-y+x > x+5+y implies y< -5

We got above y< -5 implies -y>5 Substitute this value in statement (1) we get x<=0

So ranges of x,y are y<-5 and y<x<=0

Now consider the question: Is (y-10)^2 > (x+10)^2?
y is always negative so adding a more negative value (-10) is more negative and squaring is a positive big value. On the RHS, x is negative and you are adding a positive value making the number (without sign) smaller. So square will surely be less than LHS. Even if we take highest value of x which is 0.... RHS will be less than LHS...

Hence (C)
Manager
Manager
User avatar
Joined: 20 Dec 2013
Posts: 117
Followers: 1

Kudos [?]: 41 [0], given: 1

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 02 Jan 2014, 10:49
JJ2014 wrote:
Is (y-10)^2 > (x+10)^2?

(1) -y > x+5
(2) x > y


Statement I is insufficient
- y > x + 5
x = -3, y<-2

x y (y-10)^2 (x-10)^2 result (YES/NO)
-3 -3 169 169 NO
-3 -4 196 169 YES

Statement II is insufficient
x y (y-10)^2 (x-10)^2 result (YES/NO)
-3 -4 196 169 YES
4 3 36 49 NO

Combining is sufficient (Approach should be algebraic while combining)
x > y
-y>x+5
________(Adding both the inequalities we get)
x - y > x + y + 5
y < -2.5
-y>2.5
Maximum value for -y is 2.6

2.6 > or equal to x + 5
-2.4 > or equal to x OR -2.5 > x

Since we know both the numbers are negative and x is greater than y always hence the square value will always be greater for (y-10)^2.

The answer is C.
_________________

Perfect Scores

If you think our post was valuable then please encourage us with Kudos :)

To learn GMAT for free visit:

http://Perfect-Scores.com
http://Youtube.com/PerfectScores
http://Facebook.com/PerfectScores

Expert Post
2 KUDOS received
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4668
Location: Pune, India
Followers: 1075

Kudos [?]: 4790 [2] , given: 163

Re: Is (y-10)^2 > (x+10)^2? [#permalink] New post 03 Jan 2014, 03:46
2
This post received
KUDOS
Expert's post
JJ2014 wrote:
Is (y-10)^2 > (x+10)^2?

(1) -y > x+5
(2) x > y


Responding to a pm:

The algebraic solution to this has been provided by Bunuel here: is-y-10-2-x-163368.html#p1294316

You can use the concept of mods and visualize it on the number line too.

Is (y-10)^2 > (x+10)^2?
Is |y-10| > |x+10|?

Is distance of y from 10 greater than distance of x from -10?

(1) -y > x+5
x+y < -5

________-10________x____y__________0__________________10
Yes, distance of y from 10 is greater than distance of x from -10.

__x_________________________-10______________________0____________y______10
No, distance of y from 10 is not greater than distance of x from -10.

Not Sufficient.

(2) x > y
y is to the left of x on the number line.
________-10________y____x_______0___________________10
Yes, distance of y from 10 is greater than distance of x from -10.

________-10____________________0_________y___x______10
No, distance of y from 10 is not greater than distance of x from -10.

Not Sufficient.

Using Both, y will be to the left of x and y+x < -5

________-10________y____x_______0___________________10
Yes, distance of y from 10 is greater than distance of x from -10.

__y________-10___________________0_______x_____________10
Yes, distance of y from 10 is greater than distance of x from -10.

So in any case, distance of y from 10 will be greater than distance of x from -10. Sufficient

Answer (C)
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Save $100 on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Re: Is (y-10)^2 > (x+10)^2?   [#permalink] 03 Jan 2014, 03:46
    Similar topics Author Replies Last post
Similar
Topics:
610 --> 710 --> 730 ---> DONE! dav35 1 14 May 2012, 15:09
590 -> 620 -> 560 -> [?] kituz 3 26 Mar 2012, 07:10
590 >>> 690 leamur247 6 08 Oct 2010, 04:11
DS: >? judokan 5 30 Aug 2008, 00:32
If != , is / > 1? 1> >0 2> <0 abiswas 6 02 Nov 2007, 21:17
Display posts from previous: Sort by

Is (y-10)^2 > (x+10)^2?

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.