I chose the answer to be A but the [spoiler]OA = C[/spoiler]. Please let me know why...
Thanks
Thanks
StAy HuNgry sTay fOOlisH
The key here is plugging in, rather than relying on absolute mathematical concepts, which may contain end cases that you may not think about considering. Here's how I would approach the question:
When reading the question stem, the possible answers are "yes, |x| equals y-z" or "No, |x| is not equal y-z". In DS yes/No questions, your initial approach is to try and show that the statement(s) allow for both a yes and a no, thus proving the statement insufficient. Only if you cannot reach opposite results should you then take a step back and see why the statement(s) is actually sufficient.
The absolute value in the question stem is a clue to plugging in positive and negative values for x, since |x| is always positive, but x itself may be negative: the absolute value of -5 is the same as absolute value of 5 - both are equal to 5.
So:
Stat. (1): x+y=z, or x=z-y.
If z=3 and y=2, then x=3-2=1, and then |1| is NOT equal to the question stem's y-z=2-1=-3. that's a no. Can we find a yes?
Try to plug in values of z and y that will yield a negative x:
if z=2 and y=5, then x=2-5=-3. In this case, |-3|=3 IS equal to the question stem's y-z=5-2=3, so the answer is "yes".
Since you have both a "yes" and "no" possible answers to the question, the answer is maybe: stat. (1)->Maybe-> IS.
Stat. (2): x <0 alone is meaningless.
combined: Stat. (2) effectively eliminates the "no" scenario we tried earlier (and others like it): x has to be negative, so z-y has to be negative. The absolute value of x will then be the opposite, positive value of the negative expression z-y, which is equal to -(z-y) = y-z.
