(1) If m = 15 and z = 4, then m + z = 19 > 0
If m = -9 and z = -4, then m + z = -13 < 0
No unique answer.
So, (1) is NOT SUFFICIENT.
(2) If m = 2 and z = 1, then m + z = 3 > 0
If m = -9 and z = -2, then m + z = -11 < 0
No unique answer.
So, (2) is NOT SUFFICIENT.
Combining (1) and (2), m - 3z > 0 or m > 3z and 4z - m > 0 m < 4z
So, 3z < m < 4z
If we take z = -1, then 3z < m < 4z does not hold true. It is true only for positive values of z, and when z is positive, m is also positive. hence m + z > 0
The correct answer is [spoiler](C)[/spoiler].
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
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