Data Sufficiency

DS Practice test question

are you sure the series of questions you just posted are not discussed earlier?

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IMO: D

whats OA ? - i'll explain afterwards.

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.

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]

whats the OA here guys?

-x = y -z

it cant be A.. as

x can be more than 0 also..

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

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???

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

imo c,mission mba oa please?

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.

definitely its C both the option are required to meet the given conditions..

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).

Thanks Stuart!