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OG 10th Edition 206 (DS) - Is the solution in OG Wrong!

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OG 10th Edition 206 (DS) - Is the solution in OG Wrong!

by kkrish » Thu Mar 18, 2010 9:54 pm
The question is rather simple

Is x Between 0 and 1?

1). X^2 is less than X
2). X^3 is Positive

The Official solution is A;

I have no qualms that BCD are invalid choices, but shouldn't answer choice 'E' be correct?

X^2 is less than X is true for -0.5 as well as 0.5, its not conclusive that X is indeed between 0 and 1.


Thoughts, Advise?


Cheers
K
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by papgust » Thu Mar 18, 2010 10:20 pm
if x is -0.5, then x^2 will be greater than x and not less than x.

But the statement says that x^2 < x. So, the scenario of negative fractions (such as -0.5) is disqualified.
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by harshavardhanc » Fri Mar 19, 2010 12:03 am
kkrish wrote:The question is rather simple

Is x Between 0 and 1?

1). X^2 is less than X
2). X^3 is Positive

The Official solution is A;

I have no qualms that BCD are invalid choices, but shouldn't answer choice 'E' be correct?

X^2 is less than X is true for -0.5 as well as 0.5 , its not conclusive that X is indeed between 0 and 1.


Thoughts, Advise?


Cheers
K
X^2 is less than X is true for -0.5
think about it once again. Draw the number line and plot these points , if you need to. May be your answer will change.
Regards,
Harsha
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by neoreaves » Fri Mar 19, 2010 6:56 am
1) x2 < x

x2 is always positive , thus

positive < x

thus x would be positive. This indicates 0 < x

Moreover, the only case where x2 < x is in case of fractions. Thus, 0<x<1.


Thus OG is right.


("Never question OG's Authorata": Eric Cartman) -- he didn't exactly say this but you get my point :)
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by kkrish » Fri Mar 19, 2010 10:27 am
Doh!!! Thanks; Please treat the thread closed
Last edited by kkrish on Fri Mar 19, 2010 1:11 pm, edited 1 time in total.
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by GMAT680 » Fri Mar 19, 2010 12:12 pm
Is 0 <x< 1?
Statement 2: it is only telling us X is positive. so NOT SUFF.
Statement 1: Root of X is less than x. This is always true but not for numbers between 0 and 1. the answer is not and Statement 1 is SUFF.

you can test this for x = 1/9 or 1/4 and their root value is greater because it is 1/3 and 1/2 respectively.

Hope this helps
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