gmat66
Is |x − z − y| > x − z + y?
(1) 0 < x < z < y
(2) (x – z – y) is negative
Hi,
I have been doing various GMAT problems, and one major confusion was pertaining to absolute sign problems in data sufficiency (Specifically the one mentioned below)
Using the standard approach for absolute problems, I usually interpreted the question as if x-z-y >0, Then y<0 OR if x-z-y<0, Then x<z.
However my point of confusion starts, when i start looking at the two given statements.
As per the above problem, statement 1 states that x<z - Is this only information sufficient or do we also need the condition that x-z-y<0. I am really confused at this part, in some problems, both the statements are used, and in some statements only one statement is sufficient. I am really not sure how should i go about dealing with the DS statements for these type of absolute problems.
Please clarify my confusion or let me know if i am missing out on something. Thanks you.
First check this blog post:
https://anaprep.com/algebra-the-why-beh ... questions/Question: Is |x − z − y| > x − z + y?
What is |x − z − y|? How do we evaluate it? We need to know whether x − z − y is positive or negative.
(1) 0 < x < z < yIf x is to the left of z and to the left of y on the number line, (z + y) is much greater than x so x - (z + y) is negative. Hence x - z - y is negative.
|x − z − y| = -(x - z - y) = -x + z + y
Question: Is -x + z + y > x − z + y?
Is z > x?
We are given it is hence sufficient.
(2) (x – z – y) is negativeThen |x − z − y| = -(x - z - y) = -x + z + y
Question: Is -x + z + y > x − z + y?
Is z > x?
We don't know. All we know is that (x – z – y) is negative. z may be greater than x as in statement 1 above or it may be less than x as in x = 2, z = 1 and y = 10. This also satisfies (x – z – y) is negative.
Hence statement 2 alone is not sufficient.
Answer (A)