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26 Mar 2018, 01:20
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E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
75%
(hard)
Question Stats:
45% (02:01) correct
55%
(02:05)
wrong
based on 49
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Not Attempted Yet
X, Y, Z are integers. Is 3*X > Z?
(1) X + 2*Y > 3*Z
(2) 2*Z > 2*Y - X
(1) X + 2*Y > 3*Z
(2) 2*Z > 2*Y - X
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
26 Mar 2018, 01:57
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amanvermagmat
As all we're given is equations, we'll work with equation-related tools such as simplification.
This is a Precise approach.
(1) Multiplying our inequality by 3 gives 3x+6y>9z --> 3x > 9z - 6y.
Without knowing if y is positive or negative we definitely cannot know if 3x > 9z, let alone 3x>z.
Insufficient.
(2) We'll once again try to create "3x is larger than" in our expression: Multiplying by 3 gives
6z>6y-3x --> 3x>6y-6z. Similarly to the before, we need some information about y to solve.
Insufficient.
Combined.
We'll notice that one equation has '6y' and another has '-6y'. Adding them together cancels out the y and gives
3x+3x > (3z-6y)+(6y-9z) --> 6x > -6z --> 3x > -3z.
So, to answer the question we need to know if -3z > z. But is it? If z is positive this inequality is always false and if it is negative this inequality is always true.
Insufficient.
(E) is our answer.
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26 Mar 2018, 02:29
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amanvermagmat
(1) X + 2*Y > 3*Z
Let x = 1, Y = 2 & Z = 1.......3 > 1........Answer is Yes (You can notice that you can manipulate Y easily to prove statement 1)
Let x = 1, Y = 100 & Z = 4........... 3 > 4....Answer is NO
Insufficient
(2) 2*Z > 2*Y - X
Let x = 1, Y = 1 & Z = 1.......3 > 1........Answer is Yes
Let x = 1, Y = 1 & Z = 6.......3 > 6........Answer is No
Insufficient
Combining 1 & 2
X + 2*Y > 3*Z
2*Y - X < 2*Z
-----------------------We can subtract
2X > Z
Let x = -1 & z =-3..........-3 > -3...........Answer is NO
Let x = 2 & z = 1.............6 > 1.............Answer is Yes
Insuffecient
Answer: E
