GMAT Prep Test: Is w > 1?

[Guest]

Is w > 1?

(1) w + 2 > 0
(2) w^2 > 1

Answer on test is E. I am getting C.

(1): w > -2 Insufficient
(2): w> 1 or w < -1 Insufficient

(1) and (2): Only numbers that satisfy both criteria are w > 1. I get C.

What am I missing?

[Guest]

For example, both (1) and (2) are satisfied by W=1.5 and W=-1.5. (1) and (2) together do not necessarily lead to W>1.

[RonPurewal]

Is w > 1?

(1) w + 2 > 0
(2) w^2 > 1

Answer on test is E. I am getting C.

(1): w > -2 Insufficient
(2): w> 1 or w < -1 Insufficient

(1) and (2): Only numbers that satisfy both criteria are w > 1. I get C.

What am I missing?

you're making one of the TWO DEADLY ASSUMPTIONS.

here are the TWO DEADLY ASSUMPTIONS:
1. NEVER assume that numbers are integers, unless you're told, or can infer, that they are.
2. NEVER assume that numbers are positive, unless you're told, or can infer, that they are.

you've apparently made DEADLY ASSUMPTION NUMBER ONE, because you seem to be posting under the impression that there are no numbers between -2 and -1.

there are numbers between -2 and -1, and those numbers are precisely the reason why the answer to this problem is (e).

[gmataspirant9]

Hi Ron,
I just wanted to understand one point for data sufficiency questions.
If there are two results(from statement 1 and statement 2) how to get the final result of that?
is it by using the intersection(common of both results) or by taking the union of both the results.
I specially get confused in inequality questions specially the type of questions define here and and this post:http://www.manhattangmat.com/forums/quest-for-750-quant-problem-t4868.html

If any one else can help me a little quickly(because Ron might get to this in week's time), I have my exam in next week.

[jnelson0612]

Hi Ron,
I just wanted to understand one point for data sufficiency questions.
If there are two results(from statement 1 and statement 2) how to get the final result of that?
is it by using the intersection(common of both results) or by taking the union of both the results.
I specially get confused in inequality questions specially the type of questions define here and and this post:http://www.manhattangmat.com/forums/quest-for-750-quant-problem-t4868.html

If any one else can help me a little quickly(because Ron might get to this in week's time), I have my exam in next week.

I hope your test went well, if we're not answering in time!

Briefly, if the two statements each give you various answers but there is only one common answer between them the answer would be C. For example:

What is x?
1) x^2 + x - 12 = 0
Factor: (x+4)(x-3)= 0
x=-4 or 3
Two values, not sufficient
2) x^2 + 2x -8 = 0
(x + 4)(x - 2) = 0
x=-4 or 2
Two values, not sufficient

Together:
1) x=-4 or 3
2) x=-4 or 2
Sufficient. There is only one value that is common to both, -4.

Now, let's say for example you have a different problem asking what is x and here is what you get:
1) x=3, 5, or 7
2) x=3, 5, or 6

This would be E, insufficient even when combined, because you still have two possibilities for x, 3 and 5. When you combine you have to have only one possible value satisfying both equations to be able to choose C.

Hope this helps--let us know if we can clarify further.