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Isn't it always the case that if X+Y>0 then X>-Y. I know that it's an easy one, I just can't get my mind around it. I am solving the hard questions but then my mind blocks on the easy ones.
DS question:
Is X+Y positive?
1-X-Y is positive
2-Y>0
What is the answer? C?
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BSchool Thread Master
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score780 wrote: Isn't it always the case that if X+Y>0 then X>-Y. Yes IT IS TRUE ALWAYS! X+Y > 0 take Y to the other side or subtract both the sides by Y we get: X+Y - Y > 0 - Y => X > -Y score780 wrote: DS question:
Is X+Y positive?
1-X-Y is positive
2-Y>0
Question is is X + Y > 0 STAT1 X-Y > 0 => X > Y Only thing which this option tells us is that X is greater than Y Now, X and Y can both be negative then X + Y < 0 X can be positive and Y can be negative and |Y| > |X| then X + Y <0 X can be positive and Y can be negative and |Y| = |X| then X + Y =0 X can be positive and Y can be negative and |Y| < |X| then X + Y >0 X and Y can both be positive, in this case X + Y > 0 So, NOT Sufficient STAT2 Y > 0 This is not sufficient as we have no information about X STAT1 and STAT2 together give us that X > Y and Y is positive so, obviously X will also be positive Hence, X + Y >0 (because both X and Y are positive) So, answer will be C Hope it helps!
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Joined: 24 Jul 2010
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nktdotgupta wrote:
Question is is X + Y > 0
STAT1
X-Y > 0
=> X > Y
Only thing which this option tells us is that X is greater than Y
Now, X and Y can both be negative then X + Y < 0
X can be positive and Y can be negative and |Y| > |X| then X + Y <0
X can be positive and Y can be negative and |Y| = |X| then X + Y =0
X can be positive and Y can be negative and |Y| < |X| then X + Y >0
X and Y can both be positive, in this case X + Y > 0
So, NOT Sufficient
Thank you very much. I am just confused about the statements where you included absolute values. You say X+Y can both be negative then X+Y<0, this I understand. Then you say "X can be positive and Y can be negative and |Y| > |X| then X + Y <0". Is it possible for you please to explain this and how it links to assessing if stat 1 is sufficient.
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BSchool Thread Master
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score780 wrote: nktdotgupta wrote:
Question is is X + Y > 0
STAT1
X-Y > 0
=> X > Y
Only thing which this option tells us is that X is greater than Y
Now, X and Y can both be negative then X + Y < 0
X can be positive and Y can be negative and |Y| > |X| then X + Y <0
X can be positive and Y can be negative and |Y| = |X| then X + Y =0
X can be positive and Y can be negative and |Y| < |X| then X + Y >0
X and Y can both be positive, in this case X + Y > 0
So, NOT Sufficient
Thank you very much. I am just confused about the statements where you included absolute values. You say X+Y can both be negative then X+Y<0, this I understand. Then you say "X can be positive and Y can be negative and |Y| > |X| then X + Y <0". Is it possible for you please to explain this and how it links to assessing if stat 1 is sufficient. All the cases of STAT1 with examples are explained below in detail:--
-> Now, X and Y can both be negative then X + Y < 0Ex:- X= -1 Y =-2 then, X+Y = -1 + (-2) = -3 which is less than zero so X+Y < 0 (it helps in proving that in some cases X + Y < 0 i.e. X+Y is NOT positive)-> X can be positive and Y can be negative and |Y| > |X| then X + Y <0X = 6 Y = -9 then |X| = 6 and |Y| = 9 so, |X| < |Y| so, X + Y = 6 + (-9) = -3 which is less than zero So, X + Y < 0 (it helps in proving that in some cases X + Y < 0 i.e. X+Y is NOT positive)-> X can be positive and Y can be negative and |Y| = |X| then X + Y =0X = 6, Y = -6 then, |Y| = 6 and |X| = 6 so, |X| = |Y| so, X + Y = 6 + (-6) = 0 X + Y = 0 (it helps in proving that in some cases X + Y = 0 i.e. X+Y is NOT positive)-> X can be positive and Y can be negative and |Y| < |X| then X + Y >0X= 7, Y =-3 then |X| = 7 and |Y| = 3 so, |X| > |Y| X + Y > 0 (it helps in proving that in some cases X + Y > 0 i.e. X+Y is positive)-> X and Y can both be positive, in this case X + Y > 0 X = 3, Y =4 then, X + Y = 3+4 = 7 So, X + Y > 0 (it helps in proving that in some cases X + Y > 0 i.e. X+Y is positive)So, in some cases X + Y is positive and in some case it is NOT.
So, Statement 1 is not sufficient.Hope it helps!
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Joined: 24 Jul 2010
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nktdotgupta wrote:
Question is is X + Y > 0
STAT1
X-Y > 0
=> X > Y
Only thing which this option tells us is that X is greater than Y
Now, X and Y can both be negative then X + Y < 0
X can be positive and Y can be negative and |Y| > |X| then X + Y <0
X can be positive and Y can be negative and |Y| = |X| then X + Y =0
X can be positive and Y can be negative and |Y| < |X| then X + Y >0
X and Y can both be positive, in this case X + Y > 0
So, NOT Sufficient
Thanks again. I understand all your analysis. But what I am not being able to understand is how did you make the link of stat 1 to the analysis you made on X+Y>0 and say it's insufficient.
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BSchool Thread Master
Status: If you think you can, then eventually you WILL!
Joined: 05 Apr 2011
Posts: 399
Location: India
Concentration: Finance, Marketing
GMAT 1: 570 Q49 V19
GMAT 2: 700 Q51 V31
GPA: 3
WE: Information Technology (Computer Software)
Followers: 32
Kudos [?]:
136
[1] , given: 39
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score780 wrote: nktdotgupta wrote:
Question is is X + Y > 0
STAT1
X-Y > 0
=> X > Y
Only thing which this option tells us is that X is greater than Y
Now, X and Y can both be negative then X + Y < 0
X can be positive and Y can be negative and |Y| > |X| then X + Y <0
X can be positive and Y can be negative and |Y| = |X| then X + Y =0
X can be positive and Y can be negative and |Y| < |X| then X + Y >0
X and Y can both be positive, in this case X + Y > 0
So, NOT Sufficient
Thanks again. I understand all your analysis. But what I am not being able to understand is how did you make the link of stat 1 to the analysis you made on X+Y>0 and say it's insufficient. Its because stat1 in some cases gives X + Y > 0 and in some cases gives X + Y < 0 and in one case X + Y = 0 Since, it is not giving a common answer to whether X + Y > 0 So it is insufficient to answer. Hope it helps!
_________________
ankit
you must believe
How to start GMAT preparations?
How to Improve Quant Score?
gmatclub topic tags
Check out my GMAT debrief
Thursdays with Ron link
Looking for a Quant tutor? Check out my post for the same!
Combined Formula Sheet :
Number Properties || Word Problems and PnC || Equations, Inequalities || Geometry
How to Solve :
Statistics || Reflection of a line || Remainder Problems
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