This is an explanation of the first logic game from Section III of LSAT preptest 67, the October 2012 LSAT.
Five students are delivering speeches. The five students are Manolo, Nadia, Owen, Peng and Rana (M, N, O, P, R), and the topics for the speeches are friendship and liberty (F, L).
The students have one of three majors: geology, history, or journalism (G, H, J). There are two geology majors, two history majors and one journalism major.
This is a grouping game, with two sets of variables. The students are grouped into making speeches on friendship and liberty. You also must assign majors to each of the students.
I read this setup a few times before drawing anything, as there were many variables to consider. If a game confuses you, it’s worth taking your time to decide on the best way to draw it. A diagram you draw while confused is a bad diagram.
I decided it was best to represent the two groups of speeches horizontally. Friendship has two slots because of the first rule:
I also added in the second rule: G and H are the majors of the students making friendship speeches. The order doesn’t matter, since this is not an ordering game.
Next, it’s easy to add rules 3 and 4. I’ve drawn M floating above F, because we don’t know which major M is.
Rule four says R makes a liberty speech. Again, order doesn’t matter, so I put R directly in the first spot of L.
The fifth rule says R isn’t a Geology major, so I added that too.
Lastly, P is not a Geology major, and N is a Geology major.
I didn’t include the part about R from rule 5, as I already drew that directly on the diagram. O has no rules.
We can list majors for the other two spaces. Remember that there are two geology majors, two history major and one journalism major.
So liberty needs one G, one H and one J:
R can only be J/H since they can’t be G. G and H/J fill the other spots.
N, P and M are the most restrictive elements
This game seems pretty open ended. However, the last rule is actually pretty restrictive. (The rule about N and P)
N can only be a geology major. If she speaks on friendship, she forces M to be a history major.
Likewise, P can’t be a geology major. If P speaks on friendship, M must be a geology major.
Many of the questions use local rules to restrict where N, P and M can go.
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