Confusing OG Solution
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If x and y are integers, is x > y?
1) x + y > 0
2) y^x < 0
Target question: Is x > y?
Given: x and y are integers
Statement 1: x + y > 0
There are several pairs of values that meet this condition. Here are two:
Case a: x = 2 and y = 1, in which case x > y
Case b: x = 1 and y = 2, in which case x < y
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: y^x < 0
There are several pairs of values that meet this condition. Here are two:
Case a: x = 1 and y = -1, in which case x > y
Case b: x = -3 and y = -1, in which case x < y
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined:
IMPORTANT: Statement 2 tells us that y is negative. We know this because (some positive value)^x can never evaluate to be a negative value.
So, y is negative, and statement 1 tell us that x + y > 0
In other words, x + (some negative value) > 0
From this we can conclude that x is positive.
If x is positive and y is negative, then it must be true that x > y
Since we can answer the target question with certainty, the combined statements are SUFFICIENT
Answer = C
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Brent
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Hi shibsriz,
Here's a video explanation that you should find helpful:
Click HERE to watch Rich crush this DS question
GMAT assassins aren't born, they're made,
Rich
Here's a video explanation that you should find helpful:
Click HERE to watch Rich crush this DS question
GMAT assassins aren't born, they're made,
Rich
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If x and y are integers, is x > y?
1) x + y > 0
2) y^x < 0
Statement 1: x+y > 0
It's possible that x=2 and y=1, in which case x>y.
It's possible that x=1 and y=2, in which case x<y.
INSUFFICIENT.
Statement 2: y^x < 0
Implication: y<0.
It's possible that y=-1 and x=1, in which case x>y.
It's possible that y=-1 and x=-1, in which case x=y.
INSUFFICIENT.
Statements combined:
Statement 1: x+y > 0
Statement 2: y<0
Inequalities can be ADDED, as long as the <> is facing the same direction in each inequality.
Adding together x+y>0 and 0>y, we get:
(x+y) + 0 > 0 + y
x > 0.
Since x>0, and 0>y, x>y.
SUFFICIENT.
The correct answer is C.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3