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Source: — Data Sufficiency |
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by ronaldo780 » Sun Sep 13, 2009 4:22 am
Answer choice is E.

At a first glance you can see that both statements have x^2 so they cannot really say anything about the polarity (+/-) of x.

(i) plug in x=2 or x=-2 to get n^3(1-4)<0 or (n^3)(-3)<0; n can be positive so the statement holds, but we don't know whether x is neg or pos.

(ii) x^2-1<0 is x^2<1. plug in x=-1/2 or x=1/2. still no certain polarity.

(i)+(ii) we know 1-x^2 is pos, no matter what x is. so n^3 must be neg, but that's not the question!
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by sanjib » Sun Sep 13, 2009 5:27 am
The st.2 is not very clear the way it is explained. Please.
OA is not E
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by scoobydooby » Sun Sep 13, 2009 9:57 am
guess there is a typo.
statement 1 should read x^3(1-x^2)<0
=>x^3<x^5

possible when x>1 or when x is a negative fraction
not sufficient

statement 2: x^2-1<0
=> -1<x<1
not sufficient

together, x must be a negative fraction.
hence, C
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