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Robots X, Y, and Z each assemble components at their [#permalink]
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31 Mar 2009, 17:00
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72% (01:18) correct 28% (01:08) wrong based on 446 sessions
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Robots X, Y, and Z each assemble components at their respective constant rates. If \(r_x\) is the ratio of Robot X's constant rate to Robot Z's constant rate and \(r_y\) is the ratio of Robot Y's constant rate to Robot Z's constant rate, is Robot Z's constant rate the greatest of the three? (1) \(r_x < r_y\) (2) \(r_y < 1\) OPEN DISCUSSION OF THIS QUESTION IS HERE: http://gmatclub.com/forum/robotsxyan ... 39477.html
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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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31 Mar 2009, 19:03
stmnt 1  not suffic. a<b => x/z < y/z => x< y nothing about z
stmnt 2  b<1  not suffic. nothing about a or z
let's combine  b<1 => a<b and a<1 still not sufficient, z could be >,= or < than a and/or b, and it would still satisfy stmnt 1 and 2.
I think it's E.



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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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01 Apr 2009, 01:18
for 1 and 2 a < b < 1 x/z < y/z < 1 denominator z is greater than numerator. Hence C is answer.



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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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01 Apr 2009, 02:27
I think E Lets take V as Robot Z's constant rate is Robot Z's constant rate the greatest of the three?
X:Y:Z=Va:Vb:V now to have V highest we need to know whether V is <0 or >0 V could be 2 or say, 1/2 it changes the whole picture Robots X, Y, and Z each assemble components in their respective constant rates. If a is the ration of Robot X's constant rate to Robot Z's constant rate and b is the ratio of Robot Y's constant rate to Robot Z's constant rate, is Robot Z's constant rate the greatest of the three. 1) a < b 2) b < 1
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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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01 Apr 2009, 16:39
My take is C
X:Z=a; Y:Z=b Lets start with option 2 b<1 that means Z is bigger than Y.
1 says a<b so again Z is bigger than X.
Lets solve it by statements
Y= bZ Y is b times faster than Z if b is less than 1 then Z is faster on the similar note A can deduced.
@A Nitya .... Picture will not change as long as V is greater zero and V can not be negative as rate will always be positive.



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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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01 Apr 2009, 18:03
hemantsood wrote: My take is C
X:Z=a; Y:Z=b Lets start with option 2 b<1 that means Z is bigger than Y.
1 says a<b so again Z is bigger than X.
Lets solve it by statements
Y= bZ Y is b times faster than Z if b is less than 1 then Z is faster on the similar note A can deduced.
@A Nitya .... Picture will not change as long as V is greater zero and V can not be negative as rate will always be positive. I think you reasoning is correct, the answer should be C, not E.



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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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03 Jan 2011, 21:26
We need both the information if the constant rate for Z is greater or not. 1. says that constant rate of Y is greater than X. x/z < x/y 2. says that constant rate of Y is smaller than Z. y/z <1
so we need both the information.



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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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04 Jan 2011, 03:33
ajit257 wrote: see attachment
Can some explain the reasoning behind this ques. Robots X, Y, and Z each assemble components at their respective constant rates. If rx is the ratio of robot X's constant rate to robot Z's constant rate and ry is the ratio of robot Y's constant rate to robot Z's constant rate, is robot Z's constant rate the greatest of the three? Let the rates of robots X, Y, and Z be x, y, and z respectively. Given: \(r_x=\frac{x}{z}\) and \(r_y=\frac{y}{z}\). Question is \(z>x\) and \(z>y\)? (1) \(r_x<r_y\) > \(\frac{x}{z}<\frac{y}{z}\) > \(x<y\). Not sufficient. (2) \(r_y<1\) > \(\frac{y}{z}<1\) > \(y<z\). Not sufficient. (1)+(2) As \(x<y\) and \(y<z\) then \(x<y<z\). Sufficient. Answer: C.
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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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Re: Robots X, Y, and Z each assemble components at their [#permalink]
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