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

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

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New post 10 Oct 2017, 00:52
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A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

42% (01:07) correct 58% (01:03) wrong based on 100 sessions

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Re: If xy = z, what is the value of x ? (1) y = 2z (2) z < -1  [#permalink]

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New post 10 Oct 2017, 03:28
1
Bunuel wrote:
If xy = z, what is the value of x ?

(1) y = 2z
(2) z < -1


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.
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Re: If xy = z, what is the value of x ? (1) y = 2z (2) z < -1  [#permalink]

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New post 10 Oct 2017, 10:31
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
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Re: If xy = z, what is the value of x ? (1) y = 2z (2) z < -1  [#permalink]

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New post 11 Oct 2017, 09:43
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
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Re: If xy = z, what is the value of x ? (1) y = 2z (2) z < -1  [#permalink]

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New post 23 Oct 2018, 00:40
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Re: If xy = z, what is the value of x ? (1) y = 2z (2) z < -1   [#permalink] 23 Oct 2018, 00:40
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