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Source: — Data Sufficiency |
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Re: PowerPrep DS Question

by jayhawk2001 » Mon Jul 02, 2007 9:28 pm
jrbrown2 wrote:Is RST = 1?

(1) RS = 1
(2) ST = 1

Please give an explanation.
1 - insufficient. value of RST is dependent on the value of T

2 - insufficient. value of RST is dependent on the value of R

Together, there are multiple possibilities

R=S=1 & S=T=1 which gives RST = 1

R=S=-1 & S=T=-1, which gives RST = -1

S=1/R & S = 1/T, which gives RST = 1/T

Hence insufficient. Is it E ?
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by jrbrown2 » Tue Jul 03, 2007 6:48 am
OA is E....Good explanation
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by discreet » Fri Jul 06, 2007 12:13 am
I think I have seen this question somewhere...Is it from OG 11 too?

Anyway,Jayhawk's explanation is perfect...

Just to add to that...Jayhawk has picked integer values for the variables.Sometimes,it may lead to incorrect answers.However,the statements are insufficient in all situations...

One more way to look at it...

Is RST = 1 ?
(1) says RS=1

Now,Imagine that R=1/2 and S is 2 => RS =1 and T can take any value.So, 1 alone is insufficient.

(2) same exaplantions as 1...u can assign S=2 again and
T to 1/2.Product is 1 but R can take any value.So,Insufficient.

Now taking two statements together....assume the same values as above !
R=1/2,S=2,T=1/2...Product RST is not 1 but RS,ST = 1.Hence,insufficient
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