June 2007 LSAT Section 1 Question 15

If Freedom makes a voyage to Guadeloupe in week 1 and to Trinidad in week 2, which one of the following must be true?

medasmx@protonmail.com on January 3, 2022

still dont get the explanations

G-T-M-G-M-J-T I think for A to be the answer then above has to be the sequence. I think the condition states that if you have J then you have to have G-J. Since J cant be 4 you cant have… G-T-M-G-T-M-T I suppose maybe the rule suggests that if you have J then G has to be sometime before J but it looks to me like it has to be immediately before J. Please clarify where my misunderstanding is…

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medasmx@protonmail.com on January 3, 2022

sorry the second sequence should read…
G-T-M-G-J-M-T
since J cannot be 4

Jay-Etter on January 14, 2022

Hi, yes you are correct that the correct answer sequence for this question is
G T M G J M T.

We get here by starting with
G T _ _ _ _ T, and we know we need a M-G-M somewhere from the rules, and we also need a J which must occur as GJ also based on the rules. Therefore we need M-GJ-M and we have no other options to put these in order in positions 3, 4, 5, and 6.

The key here (which you alluded to in your question) is that we have to write rule 4 as J -> GJ, and NOT simply that GJ must always be together. This is because since the variables can be repeated, and the rule just states G must precede any J, WHEN we have a J there must be a G before it resulting in J -> GJ.