inequalities

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inequalities

by teejaycrown » Sat Oct 20, 2012 12:01 pm
On the number line, the distance between x and y is greater than the distance between x and z. Does z lie between x and y on the number line.
1. Xyz < 0
2. Xy < 0
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by GMATGuruNY » Sat Oct 20, 2012 2:00 pm
teejaycrown wrote:On the number line, the distance between x and y is greater than the distance between x and z. Does z lie between x and y on the number line.
1. Xyz < 0
2. Xy < 0
The following case satisfies all of the conditions in the problem:
y=-5......................0....z=1.............x=5
Question stem condition: The distance between x and y (10) is greater than the distance between x and z (4).
Statement 2: xy = (5)(-5) = -25, with the result that xy < 0.
Statement 1: xyz = (5)(-5)(1) = -25, with the result that xyz < 0.
Here, z is between x and y.

The following case satisfies all of the conditions in the problem:
y=-5......................0.......................x=5....z=6
Question stem condition: The distance between x and y (10) is greater than the distance between x and z (1).
Statement 2: xy = (5)(-5) = -25, with the result that xy < 0.
Statement 1: xyz = (5)(-5)(6) = -150, with the result that xyz < 0.
Here, z is NOT between x and y.

Thus, the two statements combined are INSUFFICIENT.

The correct answer is E.
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by teejaycrown » Sun Oct 21, 2012 4:31 pm
This type of equation/question, what is the best strategy to approach it? Is it to try and test with various numbers like you did and if yes, how do we choose good numbers or which numbers jumped at you immediately you see the question. I have discovered that in all my practice, I always miss all the data sufficiency questions that involves variables such as x, y , z where we have to prove it with real numbers. Since, DS constitute 40% of the GMAT math problem, what a dice do you have for me to deal with DS questions.