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If wx>0, xy>0, and yz<0, is w^3*z^2<0? 1) z>0 2) x<0 [#permalink]
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09 Mar 2017, 22:36
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If \(wx>0\), \(xy>0\), and \(yz<0\), is \(w^3*z^2<0\) ? 1) \(z>0\) 2) \(x<0\)
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Re: If wx>0, xy>0, and yz<0, is w^3*z^2<0? 1) z>0 2) x<0 [#permalink]
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09 Mar 2017, 22:40
x, y and w should be of same sign. So both of statements are sufficient. Hence D. Sent from my SCV31 using GMAT Club Forum mobile app



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Re: If wx>0, xy>0, and yz<0, is w^3*z^2<0? 1) z>0 2) x<0 [#permalink]
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10 Mar 2017, 01:43
wx>0, xy>0 and yz<0. This condition holds true if w,x,y are of same sign and z is of opposite sign There fore in order to answer the question, we need the sign of atleast one variable.
St 1: z is negative. that means w,x,y are positive. therefore w^3 will be positive and z^2 will be positive and hence w^3.z^2 will be positive. ANSWER St 2: x is negative. that means w and y are negative and z is positive. hence w^3 is negative and z^2 is positive. Hence w^3.z^2 will be negative. ANSWER
Option D



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Re: If wx>0, xy>0, and yz<0, is w^3*z^2<0? 1) z>0 2) x<0 [#permalink]
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24 Aug 2017, 06:53
Because \(z^2\) is always positive, therefore the question is really asking if w<0. And wx>0 so if we know the sign of x we can answer the question.
1 z is positive => y negative => x is negative, we know the sign, SUFF 2 x<0, we know the sign, SUFF
Answer is D.



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Re: If wx>0, xy>0, and yz<0, is w^3*z^2<0? 1) z>0 2) x<0 [#permalink]
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14 Sep 2017, 14:12
My approach  marked it wrong initially, but then realized why it is D: 1) z > 0 > y * z < 0 means y is ve and z is +ve > indicates only case of x *y>0 and  w*x>0 > therefore z sq*w cube <0
2) x<0 > only case of x*y >0 > x*w> 0 (only case possible) > y*z< 0 (carrying over the sign for y) therefore w cube * z sq < 0 suff
Ans is D




Re: If wx>0, xy>0, and yz<0, is w^3*z^2<0? 1) z>0 2) x<0
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14 Sep 2017, 14:12






