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# Is x positive?

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Senior RC Moderator
Status: It always seems impossible until it's done!!
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19 Aug 2015, 02:53
5
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Difficulty:

5% (low)

Question Stats:

84% (00:46) correct 16% (00:57) wrong based on 81 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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19 Aug 2015, 04:45
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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19 Aug 2015, 06:14
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, 07:01
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Re: Is x positive? &nbs [#permalink] 16 Jul 2018, 07:01
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