If xy = z, what is the value of x ? (1) y = 2z (2) z

Question

If xy = z, what is the value of x ?
 
(1) y = 2z 
(2) z < -1

AC07 · Answer

xy = z, x = ?

Statement 1:
y = 2z
Substituting, x*2z = z
If z is not equal to 0, we can cancel it and x would be equal to 1/2. But, if z is equal to 0, x could be anything (still satisfying the given information xy = z). Since we do not know if z is equal to 0 or not, this statement is insufficient.

Statement 2:
z < -1
So, xy < -1
This statement does not give any information about x and is therefore insufficient.

Combining statements 1 and 2,
z < -1
So z is not equal to 0. z can be divided on both sides of x*2z = z
Therefore, x = 1/2

Answer is  C .

Skywalker18 · Answer

If xy = z, what is the value of x ?
 
(1) y = 2z 
x(2z) = z
=> 2x (z) = z
But we can't cancel z here as z might be equal to zero .
Not sufficient

(2) z < -1
Not sufficient

Combining 1 and 2 , we get
x = 1/2

Answer C

rajudantuluri · Answer

Given xy = z, what is x? Question can be rewritten as x = z/y 1) y = 2z --> z/y = 1/2 --> Sufficient 2) z < - 1 --> xy < -1 --> Not Sufficient since we have no information about y. Answer: A

chetan2u · Answer

xy=z
Nothing much can be done to the question stem.

(1) y=2z
xy=z…….x(2z)=z……..2xz-z=0…….z(2x-1)=0
Either z=0 or x=1/2 or both. 
 We can say for sure that x=1/2 only when   z
eq 0

(2) z<-1
Insufficient

Combined
We know z is not 0 from statement 2, so x=1/2 from statement 1.
Sufficient

C

If xy = z, what is the value of x ? (1) y = 2z (2) z < -1

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