LSAT October 1996 Section 4 Question 15 (Logical Reasoning) Forum

[lelele]

11. Rhonda will see the movie tomorrow afternoon only if Paul goes to the concert in the afternoon. Paul will not go to the concert unless Ted agrees....

The pattern of reasoning displayed above is most clearly paralleled in which one of the following texts?

(A) If Janice comes to visit, Mary will not pay the bills tomorrow. Janice will not come to visit unless she locates a babysitter. However, Janice has located a babysitter, so she will visit Mary.

(B) Gary will do his laundry tomorrow only if Peter has to go to work. Unless Cathy is ill, Peter will not have to go to work. Since Cathy is not ill, Gary will not do his laundry tomorrow.

(C) Kelly will barbecue fish tonight if it does not rain and the market has fresh trout. Although the forecast does not call for rain, the market does not have fresh trout. So Kelly will not barbecue fish tonight.

(D) Lisa will attend the family reunion next week only if one of her brothers, Jared or Karl, also attends. Karl will not attend the reunion but Jared will. So Lisa will attend the reunion.

(E) George will not go to the museum tomorrow unless Mark agrees to go. Mark will go to the museum only if he can postpone most of his appointments. Mark has postponed some of his appointments, so he will go to the museum.


Just wanted some help on this, if anyone could explain to me why B is correct!

Thanks in advance!

[imPatient285]

11. Rhonda will see the movie tomorrow afternoon only if Paul goes to the concert in the afternoon. Paul will not go to the concert unless Ted agrees to go to the concert. However, Ted refuses to go to the concert. So, Rhonda will not see the movie tomorrow afternoon.

The way I break it down from that:

Rhonda requires Paul. Paul requires Ted.

No Ted -- therefore no Rhonda (since Ted is required for Paul, and Paul is required for Rhonda).

You're looking for a similar argument with three pieces in a "requirement chain", which happens to be valid.

(B) Gary will do his laundry tomorrow only if Peter has to go to work. Unless Cathy is ill, Peter will not have to go to work. Since Cathy is not ill, Gary will not do his laundry tomorrow.

Gary requires Peter, Peter (working) requires Cathy (being ill). No Cathy, therefore no Gary (also a valid argument)

Hope this helps? When dealing with these I try to break it down into the simple logical pieces and run with it from there.