PT 12 (oct 1994) section 1 quesetion 25 Forum

[beezneez]

It starts "All actors..."

It's driving me batty. I chose E but it's B. I would love someone's input on this crazy question.

Thanks so much!

[RCinDNA]

It starts "All actors..."

It's driving me batty. I chose E but it's B. I would love someone's input on this crazy question.

Thanks so much!

This link might help: http://www.manhattanlsat.com/forums/q25 ... 540b3c2382

I usually use the LRB's Formal Logic Train/Additive Inference strategy for this, so my diagram would be:

shy <-some->actors->exuberant->extrovert

The way I would explain why answer B is correct, based on the Formal Logic Train is that you can't go backwards from extrovert to exuberant to actors because not every single extrovert is exuberant. The arrow only goes one way and that would be a mistaken reversal of the conditional logic chain we've established (i.e. since we established "that if you are an actor, then you are exuberant, and if you are exuberant then you are an extrovert", you would be mistaking the necessary for the sufficient to try and say that if you are an extrovert than you are exuberant - that doesn't have to be true).

A. We know some shy people are extroverts by just working from "shy <-some-> actors -> exuberant -> extrovert" - going from that end of the chain, it is stating "Some shy people are actors who are exuberant and extroverted" because once you cross the some chain to the other 'all' statements, everything else proceeds from the last as necessary conditions.

C. This is phrased in a funky way, but it's proceeding in the direction the ->all arrows point to: So we know some shy people are actors and because of this some actors are exuberant.

D. The contrapositive of three of the links or "stations" is "if you are not an extrovert, then you are not exuberant, if you are not exuberant you are not an actor", so "if you are not an extrovert then you are not an actor".

E. We know some extroverts are shy because "some shy people are actors, all actors are exuberant, and all exuberant people are extroverts", then some extroverts are shy actors - you're not necessarily working backwards here because we are told that some shy people have this characteristic even though the phrasing can throw off the Logic Train. It would be like drawing out "shy <-some-> extrovert"/"Some shy people are extroverts/Some extroverts are shy." which you can do because you can go across the ->s to connect the two end points.

Hope this helps - as I said, I use that method since I found it useful.

[CyanIdes Of March]

All Actors -> Exuberant -> Extrovert

Some Shy People -> Actors -> Exuberant -> Extrovert.

Since it says there are shy actors, these shy actors have to be both exuberant and extroverted. So E is wrong because some shy actors must be shy.

B, on the other hand, makes an assumption (that there are shy extroverts who aren't actors) that hasn't been explicitly stated in the stimulus. It may be that the only shy extroverts that exist are the ones who are actors.