2 more ds problems

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2 more ds problems

by xcise_science » Mon Dec 03, 2007 9:29 pm
Q20,
I'm not clear on how C is the right answer for this.

Image


Q30
stmt1: info provided on 2 tollbooths, but don't know the total # of booths, ns
stmt2: there are 4 booths, ns
But how does stmt 1&2 give us information on the middle tollbooths?
answer is C
Image
Source: — Data Sufficiency |

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by sujaysolanki » Mon Dec 03, 2007 11:19 pm
From stem xyz could each be positive or each negative

or xy could be both negative and z positive
or yz could be both negative and x positive


From 1 x and y each could be both postive or both negative

From 2 x and z each could be both postive or both negative

Combined we know X is positive

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by sujaysolanki » Mon Dec 03, 2007 11:20 pm
I think this has been discussed before ..

From 1 F-L =25 Insufficient
From 2 $ booths present in all Insufficient

Combined 25/4 < 10 HEnce sufficient

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by xcise_science » Tue Dec 04, 2007 7:22 am
Great, thanks.

With these yes/no DS questions, I really need to stop trying to find the answers and instead stop when I know I can find the answers.

for the xyz question, why couldn't we just solve for x in both stmts?
In both cases x>0, which is what we're looking for.