is robot Z’s constant rate the greatest of the three?

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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?


(1) rx < ry
(2) ry < 1
Source: — Data Sufficiency |

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by brick2009 » Sun Jul 19, 2009 12:33 pm
Ans: C

Given:
Rx/Rz = rx
Ry/Rz = ry

Is Rz > Rx and Ry?

1.) Rx/Rz < Ry/Rz => Rx < Ry, cant determine Rz (insuf)

2.) ry < 1 =>can be less than 1..only if denominator(Rz) is > Ry,
Rz > Ry... But you still cant determine if Rz > Rx..insuf

If you combine both.. rx< ry ..we can deduce... Rx < Rz

Hence.. Rz > Rx and Ry..

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by yogami » Sun Jul 19, 2009 12:36 pm
(1) gives X/Y < Y/Z or Y^2 > XZ. This says nothing about the greatness of Z ;) so insuff

(2) gives Y/Z < 1 or Y < Z. Still we dont know about X so insuff

Combine and try plugging in different numbers you should c that its suff so C IMO
200 or 800. It don't matter no more.