-
tushnir540
- Junior | Next Rank: 30 Posts
- Posts: 11
- Joined: Mon Mar 19, 2012 9:30 am
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
This is problem 44 in Data Sufficiency from the 12th Edition. For (2), even though we aren't given that the rates are positive, are we always supposed to assume that the rate is positive for rate questions? My question is revolves around (2): ry=Y/Z. Y/Z < 1 => Y < Z.
Since we don't know the sign of the rates (i.e. whether one of the robot's is actually disassembling, and thus the rate is <0 ), how are we able to multiply a variable over an inequality?
I guess we are going on an assumption that the rates are positive, but are never actually told that they are all positive. I guess my question is whether we are correct to assume that a rate is positive even if it isn't clearly stated? Thanks!
(1) rx < ry
(2) ry < 1
This is problem 44 in Data Sufficiency from the 12th Edition. For (2), even though we aren't given that the rates are positive, are we always supposed to assume that the rate is positive for rate questions? My question is revolves around (2): ry=Y/Z. Y/Z < 1 => Y < Z.
Since we don't know the sign of the rates (i.e. whether one of the robot's is actually disassembling, and thus the rate is <0 ), how are we able to multiply a variable over an inequality?
I guess we are going on an assumption that the rates are positive, but are never actually told that they are all positive. I guess my question is whether we are correct to assume that a rate is positive even if it isn't clearly stated? Thanks!
