## Help on PT 31 LG #2

Prepare for the LSAT or discuss it with others in this forum.
hellojd

Posts: 412
Joined: Wed Jan 13, 2010 1:29 pm

### Help on PT 31 LG #2

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...

worldwithoutend

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

### Re: Help on PT 31 LG #2

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: 327
Joined: Sat Mar 13, 2010 7:07 pm

### Re: Help on PT 31 LG #2

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.

Atlas LSAT Teacher

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

### Re: Help on PT 31 LG #2

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

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

### Re: Help on PT 31 LG #2

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.

Atlas LSAT Teacher

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

### Re: Help on PT 31 LG #2

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

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 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.

hellojd

Posts: 412
Joined: Wed Jan 13, 2010 1:29 pm

### Re: Help on PT 31 LG #2

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 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.