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is 0 > 0 ???

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is 0 > 0 ???

by kunalkulkarni » Fri Oct 26, 2012 6:54 pm
I know this is very basic, but thought I should get this absolutely clear. one of the GMATPrep question goes like this:

is x < 0 ?

-2x > 0
x^3 < 0

A
B
C
D
E

DS question

I was damn sure the answer is D. However, I realized it could be likely that x can also be 0.
so if x is zero, wouldn't both the above statements be false and the correct answer would then be E?
Please help me with my concept.
(any number cannot be less or greater than itself. true for the number zero). correct me if this is wrong.

Thanks,
Kunal
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by anuprajan5 » Sat Oct 27, 2012 1:05 am
Kunal,

There seems to be some real issue with the logic presented. One thing we have to understand is that the 2 statements presented are true no matter what. Their outcomes might have different results for the question - and that is something we have to deal with in DS.

I will try to deal with your confusion as well.

Question - Is x<0? In essence, this asks if x is negative.

Statement 1 - -2x>0

This statement as given in the question is fully true. We can't deny it as not being plausible. Now in this case, statement 1 can be truly only if the 2 integers in the product have the same symbol ie; negative * negative will ensure that the product is greater than 0 and positive*positive will ensure that the poroduct is greater than 0.

Since -2 is a negative integer, this statement conclusively tells me that -2x>0 only if x is also negative. Sufficient.

If x was 0, then -2x would be equal to 0 and not greater than 0, which means we are contradicting the statement.

Statement 2 - x^3 < 0

This statement tells me that a number raised to the power 3 is less than 0. This can only happen if the number is negative (regardless whether it is a fraction or an integer). Sufficient

If x was 0, then x^3 would be equal to 0 and not less than 0, which means we are contradicting the statement.

Answer D

Regards
Anup
Regards
Anup

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by kunalkulkarni » Sat Oct 27, 2012 7:10 am
Thanks Anup. you really made it easy for me to understand the question.
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