Clearly, neither statement is sufficient on its own.Rastis wrote:Is d negative?
(1) e + d = -12
(2) e - d < -12
Substituting e = -d-12 into e-d < -12, we get:
(-d-12) - d < -12
-2d - 12 < -12
-2d < 0
d > 0.
SUFFICIENT.
The correct answer is C.
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An easier explanation please
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Substituting e = -d-12 into e-d < -12, we get:
(-d-12) - d < -12
-2d - 12 < -12
-2d < 0
d > 0.
SUFFICIENT.
The correct answer is C.
Last edited by GMATGuruNY on Mon Sep 15, 2014 12:41 pm, edited 1 time in total.
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Hi Rastis,
This DS question can be solved with a bit TESTing Values and algebra:
We're asked if D is negative. This is a YES/NO question.
Fact 1: E + D = -12
If.....
E = -12, D = 0, then the answer to the question is NO
E = 0, D = -12, then the answer to the question is YES
Fact 1 is INSUFFICIENT
Fact 2: E - D < -12
If.....
E = 0, D = 13, then the answer to the question is NO
E = -100, D = -1, then the answer to the question is YES
Fact 2 is INSUFFICIENT
Combined, we have....
E + D = -12
E - D < - 12
We can combined these items using substitution; since the question is about "D", I'm going to eliminate the E:
E = -12 - D
(-12 - D) - D < -12
-12 -2D < -12
-2D < 0
D > 0
This proves that D is ALWAYS POSITIVE, so the answer to the question is ALWAYS NO.
Combined, SUFFICIENT
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
This DS question can be solved with a bit TESTing Values and algebra:
We're asked if D is negative. This is a YES/NO question.
Fact 1: E + D = -12
If.....
E = -12, D = 0, then the answer to the question is NO
E = 0, D = -12, then the answer to the question is YES
Fact 1 is INSUFFICIENT
Fact 2: E - D < -12
If.....
E = 0, D = 13, then the answer to the question is NO
E = -100, D = -1, then the answer to the question is YES
Fact 2 is INSUFFICIENT
Combined, we have....
E + D = -12
E - D < - 12
We can combined these items using substitution; since the question is about "D", I'm going to eliminate the E:
E = -12 - D
(-12 - D) - D < -12
-12 -2D < -12
-2D < 0
D > 0
This proves that D is ALWAYS POSITIVE, so the answer to the question is ALWAYS NO.
Combined, SUFFICIENT
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
