MGMAT Advanced DS Problem

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MGMAT Advanced DS Problem

by rinoa » Tue Mar 13, 2012 9:05 pm
This is from the book by Manhattan GMAT. This may be a really stupid question, but I'm not understanding why statement 1 is insufficient for this problem:

If yz =/ 0 (cannot equal 0), is 0<y<1?

1) y < 1/y
2) y = z^2
Source: — Data Sufficiency |

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by rinoa » Tue Mar 13, 2012 11:00 pm
Justtt kidding! Figured out my silly error.

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by killer1387 » Tue Mar 13, 2012 11:12 pm
rinoa wrote:This is from the book by Manhattan GMAT. This may be a really stupid question, but I'm not understanding why statement 1 is insufficient for this problem:

If yz =/ 0 (cannot equal 0), is 0<y<1?

1) y < 1/y
2) y = z^2
1) for y>0
y^2<1=> -1<y<1
ie. 0<y<1

for y<0
y^2>1
=> y<-1 and y>1
hence y<-1

hence insufficient
as for y>0 answer to required question is YES
and for y<0 answer is NO.

HTH