This is an explanation of the fourth logic game from Section I of LSAT Preptest 30, the December 1999 LSAT.
A factory with seven assembly lines will assemble seven toy-truck models (F, G, H, J, K, M, S). Each line will assemble exactly one model. You must determine the possible assignments of the toy trucks to lines.
This is a linear game, with a few sequencing rules. It can, and should, be drawn using two diagrams.
The first two rules are simple. Here’s how to draw them:
The lines between F – J tells us that F comes at some point earlier than J. MG are in a box so that we know M comes directly before G.
I draw the third rule on two diagrams:
(I added the 4th rule too)
Drawing two separate scenarios makes the game easier to visualize. On individual questions, there are often different deductions for each diagram. You should reproduce this diagram for local rule questions.
It should only take 8-10 seconds to redraw the entire diagram, if done correctly. I often avoid drawing numbers, for example. This is a very common diagram, and not hard to get used to without numbers, if you try (I keep them in here because they make the explanations clearer).
8-10 seconds is well worth the benefit of having a full diagram.
That’s the whole setup. The only other thing you should note is that there are no rules for K. You can draw a circle around K in your list of variables.
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