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Updated on: 30 Mar 2020, 00:15
Originally posted by davidfrank on 26 Oct 2014, 17:23.
Last edited by Bunuel on 30 Mar 2020, 00:15, edited 2 times in total.
Last edited by Bunuel on 30 Mar 2020, 00:15, edited 2 times in total.
Renamed the topic and edited the question.
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A
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If x y and z are positive is xz = 7xy ?
(1) z/y = 7
(2) x/y = 1
(1) z/y = 7
(2) x/y = 1
I am getting OA as D if I subsititute x=y, I get \(yz=7y^2=>z=7y\)
What am I missing here
What am I missing here
26 Oct 2014, 20:49
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To solve such type of questions we need to simplify the final question as much as possible
we need to find if xz=7xy ?
Simplifying the equation:
xz-7xy=0
x(z-7y)=0
If the options give us answers which state ,x=0 or z=7y then we can conclude that xz=7y.
Given x =positive so we need to find z=7y.
Option A : z/y=7 or z=7y ... as x,y and z are positive we know that x cannot be zero
So A is sufficient
Option B: x/y=1, as we dont know z we cannot prove xz=7xy as z is an unknown quantity.
So B insufficient
we need to find if xz=7xy ?
Simplifying the equation:
xz-7xy=0
x(z-7y)=0
If the options give us answers which state ,x=0 or z=7y then we can conclude that xz=7y.
Given x =positive so we need to find z=7y.
Option A : z/y=7 or z=7y ... as x,y and z are positive we know that x cannot be zero
So A is sufficient
Option B: x/y=1, as we dont know z we cannot prove xz=7xy as z is an unknown quantity.
So B insufficient
27 Oct 2014, 02:33
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If x y and z are positive is xz = 7xy ?
(1) z/y = 7 --> z = 7y. Substitute the value of z in the question: is x(7y) = 7xy. Since LHS and RHS are the same then the answer to the question is YES. Sufficient.
(2) x/y = 1 --> x = y. Substitute the value of y in the question: is xz = 7x^2 ? --> is z = 7x ? Since we cannot answer this question neither with a definite YES nor with a definite NO, the statements is not sufficient.
Answer: A.
Hope it's clear.
(1) z/y = 7 --> z = 7y. Substitute the value of z in the question: is x(7y) = 7xy. Since LHS and RHS are the same then the answer to the question is YES. Sufficient.
(2) x/y = 1 --> x = y. Substitute the value of y in the question: is xz = 7x^2 ? --> is z = 7x ? Since we cannot answer this question neither with a definite YES nor with a definite NO, the statements is not sufficient.
Answer: A.
Hope it's clear.
