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13 Apr 2018, 02:02
Kudos
Bookmarks
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
74% (01:32) correct
26%
(01:49)
wrong
based on 100
sessions
History
Date
Time
Result
Not Attempted Yet
If xyz ≠ 0, is xyz > 0?
(1) xz < 0
(2) x + y + z = 0
(1) xz < 0
(2) x + y + z = 0
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
13 Apr 2018, 03:14
Kudos
Bookmarks
IMO E
ST 1
either of x or z is +ve
but we don't know about y
insufficient
St2
can't predict the signs
insufficient
combining
x=-5 y=2 z=3 xyz<0
x=3 y=-1 z=-2 xyz>0
insufficient
ST 1
either of x or z is +ve
but we don't know about y
insufficient
St2
can't predict the signs
insufficient
combining
x=-5 y=2 z=3 xyz<0
x=3 y=-1 z=-2 xyz>0
insufficient
Bunuel
Important points:
1. xyz=/ 0. it means none of xyz are o.
we are looking for xyz>0.
statement 1: xz<0. we can conclude that one of z or x is negative. no information regarding y which could be negative or positive. Not sufficient.
statement 2: x+y+z=0. we know that none of the properties is 0. another point to be noted that all 3 can be negative. Thus it is a combo of both negative and positive.
case 1: x=-6
y=-6
z=12
x+y+z=0
-6-6+12=0
case 2: x=-6
y=12
z=-6
x+y+z=0
-6+12-6=0
case 3: x=12
y=-6
z=-6
x+y+z=0
12-6-6=0
try to analyze more: x=12
y=12
z=-24
12+12-24=0
so ultimately it is impossible to determine how many negative properties we have. It could be 2 or 1.
combining strategies: from 1 we can conclude that either x or z is negative. from 2 we know either any of the 2 or 1 properties has negative value. common thing in both statement is that one of the property could be negative. If only a property is negative xyz will not be greater that 0.
Thus, the best answer is C.
