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DS Practice test question #10

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Source: — Data Sufficiency |
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by aim-wsc » Fri Aug 29, 2008 6:50 am
are you sure the series of questions you just posted are not discussed earlier?

Do use search feature & kindly add keywords in the title of the thread so that it'd help other members search /seek your thread in future :)
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by California4jx » Fri Aug 29, 2008 8:20 am
IMO: D

whats OA ? - i'll explain afterwards.
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by parallel_chase » Fri Aug 29, 2008 6:50 pm
I think the answer should be C.

lxl = y-z ?

Statement I

x+y=z

x=z-y
-x=y-z

Insufficient.


Statement II

x<0
we dont know anything about y and z.

Insufficient.

Combining I & II

x<0
-x=y-z

lxl=y-z

hence sufficient.
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discuss explanation by parallel_chase

by ashish1354 » Fri Aug 29, 2008 11:56 pm
if we deduce -x=y-z
from 1 then it is sufficient to say that y-z is not =lxl

please suggest if i am wrong
so answer is A[/list]
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by sumithshah » Tue Sep 09, 2008 10:33 pm
whats the OA here guys?
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it cant be a

by Aspirant008 » Tue Sep 09, 2008 10:43 pm
-x = y -z

it cant be A.. as

x can be more than 0 also..
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by mehravikas » Tue Sep 09, 2008 11:06 pm
Even if x is greater than 0, |x| should lead to the same value in case of -x or +x.

Please correct me if I am wrong. Answer should be A
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by rosh26 » Wed Sep 10, 2008 11:38 am
From the stem: x=y-z if x is positive; x= z-y or x+y=z if negative

Stmt 1: x+y = z

But it is unknown whether x is positive or negative - INSUFF

Stmt 2:

x is negative -INSUFF

Stmts 1& 2, x+y=z, and x is neg - SUFF

Answer should be C.

What is OA???
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by mim3 » Wed Sep 10, 2008 1:47 pm
Might as well throw my two cents in...

I think it's A.

1. x+y=z
You can manipulate the first statement to get:
x= z-y
multiplying both sides by -1 we get:
-x=y-z
The opposite of x is the same thing as the absolute value of x, so 1 is sufficient.

2. x<0
Doesn't tell us anything. we can pick any numbers or x, y or z. Insufficient.

so, IMO A
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by gmatguy16 » Wed Sep 10, 2008 3:56 pm
imo c,mission mba oa please?
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Re: discuss explanation by parallel_chase

by nitin86 » Thu Sep 11, 2008 9:18 am
ashish1354 wrote:if we deduce -x=y-z
from 1 then it is sufficient to say that y-z is not =lxl

please suggest if i am wrong
so answer is A[/list]
I think that's not the case.

It depends whether x >= 0 or not.

If X >= 0, then |x| = x
If X<0, then |x| = -x

therefore, if x < o, then -x = y-z is equal to |x| = y-z
but if x>= 0, then -x = y-z is NOT equal to |x| = y-z which is equal to x=y-z

but since we don't know, whether x>=0 or X<0, we can't completely say that statement I solves the problem

I think you are misunderstanding with answer "No" to a question is also an answer ....concept.
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IMO C

by karthikgmat » Thu Sep 11, 2008 4:11 pm
definitely its C both the option are required to meet the given conditions..
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by Stuart@KaplanGMAT » Sat Nov 29, 2008 11:26 am
The correct answer is (C).

The problem with statement (1) is that we don't know the signs. Let's pick numbers to illustrate.

Does |x| = y - z

Before looking at the statements, let's note that |x| is never negative. So, if z > y, there's no way the two sides can be equal.

(1) x = z - y

Well, we could pick:
x = -3
z = 2
y = 5
(-3 = 2 - 5)

Plugging in:

Does |-3| = 5 - 2? YES

We could also pick:

x = 3
z = 5
y = 2
(3 = 5 - 2)

Does |3| = 2 - 5? NO

Since we can get both a yes and a no answer, (1) is insufficient.

However, if we know that x is negative (statement (2)), then we know from statement (1) that y > z and that the two sides WILL be equal.

Separately the statements are insufficient, together sufficient: choose (C).
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by cramya » Sat Nov 29, 2008 11:39 am
Thanks Stuart!
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