Problem Solving

Vincent Vega wrote:15. If / x / > / y / > / z /, which of the
following equations CANNOT holdtrue?

(A) x + y = 0
(B) y - z = 0
(C) xyz = 0
(D) x - y = z
(E) xyz = 1

[spoiler]OA:B[/spoiler]

* /x/ = absolute x

mohit11 wrote:
Hi mohit,
I agree with everything you wrote except this:

3. xyz=0 , Let x,y,z be 2, 0 -1 xyz= 0 , hence eliminate

x=2
y=0
z= -1
so / y / < / z /

the only way this equation holds true with the premise is that z = 0. If you check Princeton's answer, it says any of them could be 0, which is not true.

There was another question on the Verbal section that the answer was 'A' and on the answer sheets stated 'B'. On the explanation page, It said' B' but with A's choice. Simple typo I guess, but its making me reluctant about studying from that book.

Ian Stewart wrote:

Vincent Vega wrote: This question original answer is B. Is from Peterson's Master the GRE 2009 book. I'm taking the GRE and this is by far one of the best forums out there so... GRE invasion.

'15. The correct answer is (B). For equation (B) to hold true, y must equal z, which is impossible given that / y / > / z /. Equation (A) could be true because it is possible that x = -y. Equation (C) could hold true because it is possible that any one of the three variables could equal 0 (zero). Equation (D) could hold true-for example, if x = 3, y = 2, and z = 1. Equation (E) could hold true-for example if x = 2, y = 1, and z = 1 / 2'

Unless one of the inequalities is a 'greater than or equal' inequality, then your analysis is perfect, and A and B are both good answers.

Vincent Vega wrote:If you check Princeton's answer, it says any of them could be 0, which is not true.

Yes, again, you're right, and they are not. It sounds like you understand the content better than the author of the book, so I'd recommend you try working from different material

And you may want to clarify which book you're using, since you first mentioned 'Peterson', then later 'Princeton', and those are two completely different companies. It may help others here to know which resources contain errors like the ones quoted in this thread.

mohit11 wrote:Ian i have a small query,

I've been scoring at the 45- 46 level consistently. There are two problems for me not reaching the 50-51 level. A) Careless mistakes 2) Poor time management.

Do you think that people who score 50-51 are just quicker than others? or that they guess early on to avoid having 12 mins remaining for the last 6-7 questions. I would be interested in hearing your take on this.