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# Is x positive?

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Current Student
Status: It always seems impossible until it's done!!
Joined: 29 Aug 2012
Posts: 1123
Location: India
WE: General Management (Aerospace and Defense)

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19 Aug 2015, 01:53
6
00:00

Difficulty:

5% (low)

Question Stats:

85% (00:55) correct 15% (01:10) wrong based on 90 sessions

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Is x positive?

(1) $$xy^2z^3$$ = 800

(2) $$xy^2z^4$$ = 1600

Source : Aristotle Prep

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CEO
Joined: 20 Mar 2014
Posts: 2633
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)

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19 Aug 2015, 03:45
Gnpth wrote:
Is x positive?

(1) $$xy^2z^3$$ = 800

(2) $$xy^2z^4$$ = 1600

Source : Aristotle Prep

Is x>0?

Per statement 1, sign of y >0 for all y but as the product $$xy^2z^3$$ >0 ---> either x<0 and z<0 or x>0 or z>0. Thus we get a "yes" or "no" for is x>0. This statement is not sufficient.

Per statement 2, signs of y and z will not impact the equation given and as $$xy^2z^4$$ > 0 ---> x >0. Thus this statement is sufficient to answer a "yes" for is x>0.

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Joined: 14 Mar 2014
Posts: 146
GMAT 1: 710 Q50 V34

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19 Aug 2015, 05:14
Gnpth wrote:
Is x positive?

(1) $$xy^2z^3$$ = 800

(2) $$xy^2z^4$$ = 1600

Source : Aristotle Prep

Ans : B

St 1: $$xy^2z^3$$ = 800

All x,y,z can be positive
x & z both can be negative
Two possible cases. Hence not suff

St 2: $$xy^2z^4$$ = 1600

$$y^2 >0 , z^4 >0$$ , Thus x must also be >0 since their product is >0
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16 Jul 2018, 06:01
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
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Re: Is x positive? &nbs [#permalink] 16 Jul 2018, 06:01
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