Help on PT 31 LG #2

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hellojd
Posts: 411
Joined: Wed Jan 13, 2010 1:29 pm

Help on PT 31 LG #2

Postby hellojd » Tue Mar 16, 2010 9:47 pm

Hey guys,

Really struggling on this LG, particularly questions 12-13. Could someone please assist?

On 12, I don't have any inference to use...

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worldwithoutend
Posts: 67
Joined: Wed Aug 26, 2009 3:56 pm

Re: Help on PT 31 LG #2

Postby worldwithoutend » Wed Mar 17, 2010 12:04 am

I must miss these...

Question 12 comes down to the fourth rule: ~Nj + ~Uj --> Np

We know that Np (New pop) is NOT on sale, because Ns is the only new CD on sale.

The contrapositive of the fourth rule is: ~Np --> Nj OR Uj (or both)

So one of Nj or Uj MUST be on sale. And we know that it CAN'T be Nj, because Np is the only New CD.

Therefore, Uj must be on sale.

waxecstatic
Posts: 314
Joined: Sat Mar 13, 2010 7:07 pm

Re: Help on PT 31 LG #2

Postby waxecstatic » Fri Mar 19, 2010 12:00 pm

hellojd wrote:Hey guys,

Really struggling on this LG, particularly questions 12-13. Could someone please assist?

On 12, I don't have any inference to use...


Oh yeah, the CD game is one of the toughest games I've seen. Need to know the either or as well as "and" contrapositives and even then you have to make a lot of inferences to get anywhere.

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Atlas LSAT Teacher
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Joined: Tue May 12, 2009 10:18 am

Re: Help on PT 31 LG #2

Postby Atlas LSAT Teacher » Fri Mar 19, 2010 5:16 pm

The diagram I'm attaching makes people balk, but if you know our diagram system, it really breaks this game apart. Tough game though -- sort of a classic in the ass-kicker category. http://www.atlaslsat.com/forums/june-20 ... e53af67adc

r6_philly
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Joined: Sat Dec 19, 2009 4:32 pm

Re: Help on PT 31 LG #2

Postby r6_philly » Sat Mar 20, 2010 1:52 am

That diagram is over complicated. I wrote logical statements that are very easy to follow.

conditions:
Pu + Pn -> Su + Sn
Ju + Jn -> !Ru + !Rn
!Ju + !Jn -> Pn
Ru/Rn -> !Su + !Sn

So 12:

if Sn is only new type then
!Jn + !On + !Rn + !Pn
!Pn -> Ju/Jn (rule 3), because Jn not onsale (see line above) then Ju must be on sale.

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Atlas LSAT Teacher
Posts: 283
Joined: Tue May 12, 2009 10:18 am

Re: Help on PT 31 LG #2

Postby Atlas LSAT Teacher » Sat Mar 20, 2010 8:21 am

r6_philly wrote:That diagram is over complicated.
Yup, it is a doozy! Every diagram system has its weakness, and this game exposes the weakness of this one.

Nice clean write-up.

r6_philly
Posts: 10707
Joined: Sat Dec 19, 2009 4:32 pm

Re: Help on PT 31 LG #2

Postby r6_philly » Sat Mar 20, 2010 10:21 am

Atlas LSAT Teacher wrote:
r6_philly wrote:That diagram is over complicated.
Yup, it is a doozy! Every diagram system has its weakness, and this game exposes the weakness of this one.

Nice clean write-up.


lol when I see stuff like that my brain wants to take a walk outside :lol: it is helpful to figure out the logical connections between multiple, overlapping conditions by drawing diagrams, but I think only during studying. By the time one takes the real test they should be able to see the logical conclusions and inferrences without writing them out. From a computer programmer point of view, this game is super easy because it is just a set of if/then/else statements. The trick to 12 is to infer that all other new cds are not on sale, writing the ! statement down can help you go through the conditions quickly. So is 13.

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hellojd
Posts: 411
Joined: Wed Jan 13, 2010 1:29 pm

Re: Help on PT 31 LG #2

Postby hellojd » Mon Mar 22, 2010 12:03 pm

r6_philly wrote:
Atlas LSAT Teacher wrote:
r6_philly wrote:That diagram is over complicated.
Yup, it is a doozy! Every diagram system has its weakness, and this game exposes the weakness of this one.

Nice clean write-up.


lol when I see stuff like that my brain wants to take a walk outside :lol: it is helpful to figure out the logical connections between multiple, overlapping conditions by drawing diagrams, but I think only during studying. By the time one takes the real test they should be able to see the logical conclusions and inferrences without writing them out. From a computer programmer point of view, this game is super easy because it is just a set of if/then/else statements. The trick to 12 is to infer that all other new cds are not on sale, writing the ! statement down can help you go through the conditions quickly. So is 13.


Thanks a lot for the help guys. Glad to know I wasn't just imagining that this game was hard haha.




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