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!
_________________
Ankit
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How to Solve :
Statistics || Reflection of a line || Remainder Problems || Inequalities