-
Fatehdeep Singh
- Junior | Next Rank: 30 Posts
- Posts: 10
- Joined: Fri Feb 19, 2010 7:05 am
- Thanked: 2 times
Doubt With OA
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
-
sivaelectric
- Master | Next Rank: 500 Posts
- Posts: 439
- Joined: Sat Aug 09, 2008 8:32 am
- Location: India
- Thanked: 34 times
- Followed by:28 members
IMO A
If I am wrong correct me 
, If my post helped let me know by clicking the Thanks button 
.
Chitra Sivasankar Arunagiri
, If my post helped let me know by clicking the Thanks button .Chitra Sivasankar Arunagiri
-
cans
- Legendary Member
- Posts: 1309
- Joined: Mon Apr 04, 2011 5:34 am
- Location: India
- Thanked: 310 times
- Followed by:123 members
- GMAT Score:750
x>y^2?
I) x>y+5 - suppose y=1, x>6 and x>1^2
if y=9, x>14 we can't say that x>81.
Thus A insufficient.
II)x^2 - y^2 =0
=> either x=y or x=-y
now if x=y, and x=y=1, x>y^2 not true
x=y=0.5, x>y^2 true,
Thus B alone not sufficient.
A&B together,
x>y+5 => x not equal to y, thus x=-y
x>-x+5 => x>5/2
Now to find if x>y^2 or to find if x>(-x)^2 or to find if x > x^2
As x>2.5, thus x < x^2
Thus not true. Sufficient
Hence C.
I) x>y+5 - suppose y=1, x>6 and x>1^2
if y=9, x>14 we can't say that x>81.
Thus A insufficient.
II)x^2 - y^2 =0
=> either x=y or x=-y
now if x=y, and x=y=1, x>y^2 not true
x=y=0.5, x>y^2 true,
Thus B alone not sufficient.
A&B together,
x>y+5 => x not equal to y, thus x=-y
x>-x+5 => x>5/2
Now to find if x>y^2 or to find if x>(-x)^2 or to find if x > x^2
As x>2.5, thus x < x^2
Thus not true. Sufficient
Hence C.
GMAT/MBA Expert
-
Anurag@Gurome
- GMAT Instructor
- Posts: 3835
- Joined: Fri Apr 02, 2010 10:00 pm
- Location: Milpitas, CA
- Thanked: 1854 times
- Followed by:523 members
- GMAT Score:770
Solution:Fatehdeep Singh wrote:x > y^2 ?
I) x>y+5
II)x^2 - y^2 =0
OA after some discussions?
Consider first I alone.
Let x = 5 and y = -1.
Here (x = 5) > (y+5 = -1+5 = 4) and (x = 5) > (y^2 = 1).
Next let x = -1/3 and y = -6.
Now, -1/3 = x > -6+5 = -1.
But x = -1/3 < y^2 = 36.
So, nothing definite can be said from (1) alone.
Next consider II) alone.
Let x = -1 and y = 1.
So, x = -1 < y^2 = 1.
Next, let x = 1/2 and y = 1/2.
So, x = ½ > y^2 = ¼.
Again, nothing definite can be said from (2) alone.
Lastly, combine both statements and check.
If x > y+5, we get that x > y.
Or x is not equal to y.
Now II means that (x+y)(x-y) = 0.
This means that x = -y.
Now, x > y+5 means that -y > y+5 or y < -5/2.
Now x > y^2 means that -y > y^2 or y^2+y < 0 or -1<y<0.
This is not possible because y <-5/2.
So, the answer to the main question is "no".
Or, both statements together are sufficient to answer the question.
The correct answer is (C).
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
-
sivaelectric
- Master | Next Rank: 500 Posts
- Posts: 439
- Joined: Sat Aug 09, 2008 8:32 am
- Location: India
- Thanked: 34 times
- Followed by:28 members
Can someone please explain why this procedure is wrong?Fatehdeep Singh wrote:x > y^2 ?
I) x>y+5
II)x^2 - y^2 =0
OA after some discussions?
X>Y+5
X-Y>5, we can take X=7 and Y=1 so that X-Y more than 5. now X = 7 > Y^2 = 1
@Anurag Sir, can you please correct me?
If I am wrong correct me , If my post helped let me know by clicking the Thanks button .
Chitra Sivasankar Arunagiri
, If my post helped let me know by clicking the Thanks button .Chitra Sivasankar Arunagiri
GMAT/MBA Expert
-
Anurag@Gurome
- GMAT Instructor
- Posts: 3835
- Joined: Fri Apr 02, 2010 10:00 pm
- Location: Milpitas, CA
- Thanked: 1854 times
- Followed by:523 members
- GMAT Score:770
If you are just considering statement I, this example is fine but if you are combining and checking, then x^2 = 49 is not equal to y^2 = 1. So condition in II is not being satisfied.sivaelectric wrote:Can someone please explain why this procedure is wrong?Fatehdeep Singh wrote:x > y^2 ?
I) x>y+5
II)x^2 - y^2 =0
OA after some discussions?
X>Y+5
X-Y>5, we can take X=7 and Y=1 so that X-Y more than 5. now X = 7 > Y^2 = 1
@Anurag Sir, can you please correct me?
This example will not hold then.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
-
sivaelectric
- Master | Next Rank: 500 Posts
- Posts: 439
- Joined: Sat Aug 09, 2008 8:32 am
- Location: India
- Thanked: 34 times
- Followed by:28 members
Sir, But when you get an answer with the first one itself, should you have to go for the second one. But as I type this I am also starting to get another doubt about this.
When the first hint gives you an answer, should you check the same values with the second one too? Is it like that?
When the first hint gives you an answer, should you check the same values with the second one too? Is it like that?
If I am wrong correct me , If my post helped let me know by clicking the Thanks button .
Chitra Sivasankar Arunagiri
, If my post helped let me know by clicking the Thanks button .Chitra Sivasankar Arunagiri
GMAT/MBA Expert
-
Anurag@Gurome
- GMAT Instructor
- Posts: 3835
- Joined: Fri Apr 02, 2010 10:00 pm
- Location: Milpitas, CA
- Thanked: 1854 times
- Followed by:523 members
- GMAT Score:770
sivaelectric wrote:Sir, But when you get an answer with the first one itself, should you have to go for the second one. But as I type this I am also starting to get another doubt about this.
When the first hint gives you an answer, should you check the same values with the second one too? Is it like that?
You are not going to get the answer with just this example.
Take x =-1/3 and y = -6.
Here also x=-1/3 > y+5 = -1 but x = -1/3 < y^2 = 36.
This means I being true does not mean that x > y^2.
Or I alone is not sufficient.
Now, check II alone.
Take values that satisfy only II and have nothing to do with I.
Again you will not get a definite answer.
This means that II alone is not sufficient.
Next check with values that satisfy both I ans II simultaneously.
Then try to get the answer to the main question.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
-
sivaelectric
- Master | Next Rank: 500 Posts
- Posts: 439
- Joined: Sat Aug 09, 2008 8:32 am
- Location: India
- Thanked: 34 times
- Followed by:28 members
Great explanation Anurag Sir
If I am wrong correct me , If my post helped let me know by clicking the Thanks button .
Chitra Sivasankar Arunagiri
, If my post helped let me know by clicking the Thanks button .Chitra Sivasankar Arunagiri
