Carlystern
Thanks Received: 1
Jackie Chiles
Jackie Chiles
 
Posts: 41
Joined: December 22nd, 2012
 
 
 

Q15 - Rhonda will see the movie tomorrow...

by Carlystern Fri Apr 05, 2013 5:01 pm

PC = Paul goes to concert
RM = Rhonda will see the movie
TAC = Ted agrees to go to concert

PC --> RM
TAC --> PC
~TC --> ~RM

Is this the correct set up?

I am just beginning.....I need help.
 
Carlystern
Thanks Received: 1
Jackie Chiles
Jackie Chiles
 
Posts: 41
Joined: December 22nd, 2012
 
 
 

Re: Q15 - Rhonda will see the movie tomorrow...

by Carlystern Fri Apr 05, 2013 5:03 pm

Or....is it:

PC --> RM
TC --> PC

Therefore, ~TC --> ~RM

:?
User avatar
 
ManhattanPrepLSAT1
Thanks Received: 1909
Atticus Finch
Atticus Finch
 
Posts: 2851
Joined: October 07th, 2009
 
 
 

Re: Q15 - Rhonda will see the movie tomorrow...

by ManhattanPrepLSAT1 Fri Apr 05, 2013 5:22 pm

Remember, "only if" introduces something necessary...
Stimulus:
RM --> PC
PC --> TC
~TC
----------
~RM

(A)
JV --> ~MPB
JV --> JLB
JLB
--------------
JV
*wrong because this does not contain two conditionals that link using the transitive property

(B)
GL --> PW
~CI --> ~PW
~CI
----------------
~GL
*correct because the two conditionals link using the transitive property and the situation utilizes the contrapositive of the linked conditionals

(C)
~R + FT --> BF
~FT
------------------
~BF
*wrong because this negates the conditional relationship

(D)
LA --> JA or KA
~KA + JA
-----------------
LA
*wrong because this reverses the conditional relationship

(E)
GM --> MM
MM --> MPMA
MPSA
---------------
MM
*wrong because the conclusion should be about George, we don't know whether Mark has postponed "most" of his appointments, and this reverses the conditional relationship!
 
Carlystern
Thanks Received: 1
Jackie Chiles
Jackie Chiles
 
Posts: 41
Joined: December 22nd, 2012
 
 
 

Re: Q15 - Rhonda will see the movie tomorrow...

by Carlystern Fri Apr 05, 2013 5:32 pm

So, the necessary cue is obviously "only if" which is PAUL (and what he does) - the "only if" is the right side and indicates that the right side of "only if" should remain on the right? I guess I'm trying to find a pattern and I think I have something confused.

Rhonda will see the movie tomorrow afternoon ONLY IF Paul goes to the concert in the afternoon.

RM (sufficient) --> PC (necessary)

Am I understanding that correctly?
 
Carlystern
Thanks Received: 1
Jackie Chiles
Jackie Chiles
 
Posts: 41
Joined: December 22nd, 2012
 
 
 

Re: Q15 - Rhonda will see the movie tomorrow...

by Carlystern Fri Apr 05, 2013 5:55 pm

I just had an "aha!" moment. Wow.

RM --> PC
PC --> TC (~TC --> ~PC) <-----that was my "aha!" moment.
~TC
------------
~RM


So, the answer:

GL --> PW
~CI --> ~PW
~CI
---------------
~GL

I'm not automatically considering the contrapositive!!!!
 
patrice.antoine
Thanks Received: 35
Atticus Finch
Atticus Finch
 
Posts: 111
Joined: November 02nd, 2010
 
 
 

Re: Q15 - Rhonda will see the movie tomorrow...

by patrice.antoine Fri Apr 05, 2013 7:25 pm

Here is a trick I utilize:

Whenever I see "only" or "only if" I automatically place a right arrow underneath the phrase (---->) which indicates to me that the sentence that follows is our necessary portion. This also applies to sentences that start with "only" and "only if".

Keep in mind, however that "IF only" and "THE only" introduces our sufficient.
User avatar
 
ManhattanPrepLSAT1
Thanks Received: 1909
Atticus Finch
Atticus Finch
 
Posts: 2851
Joined: October 07th, 2009
 
 
 

Re: Q15 - Rhonda will see the movie tomorrow...

by ManhattanPrepLSAT1 Fri Apr 05, 2013 8:37 pm

Great trick Patrice!!!