Math questions from any Manhattan Prep GMAT Computer Adaptive Test.
mirzank
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Two Absolutes

by mirzank Thu Dec 08, 2011 10:31 pm

Got this question on my CAT 4

Is x > 0?

(1) |x + 3| < 4

(2) |x - 3| < 4

The ranges I get for 1 are -7<x<1
and from statement 2 are -1<x<7

Combining these two we get -1<x<1

The solution states that 1 and 2 together are not sufficient. thats how I answered as well at first glance, but when i reviewed I figured if -1<x<1, then x must be 0, since the inequality is just greater and less than, not greater than or equal to or less than or equal to.

So what makes both statements together insufficient? The official answer states "we still can't tell if x is positive", so insufficient. but since x is 0 based on inequality, then our answer to "is x greater than 0" would be "no, x is not greater than 0 (since it is 0) and thus sufficient.

can someone please explain.
mirzank
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Re: Two Absolutes

by mirzank Thu Dec 08, 2011 10:37 pm

ok just answered my own question. Not explicitly stated that X is an integer thus x could be decimal between -1 and 0 or 0 and 1.
tim
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Re: Two Absolutes

by tim Tue Dec 13, 2011 2:49 am

Okay let us know if you need any further help with this one..
Tim Sanders
Manhattan GMAT Instructor

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