This is an explanation of the first logic game from Section III of LSAT Preptest 77, the December 2015 LSAT.
Six entertainers are scheduled to perform on the opening day of a community festival. The performers are Robinson, Shahpari, Tigay, Wu, Yeaton, and Zane (R, S, T, W, Y, Z). Each entertainer will perform, and there are six times available, three in the morning, and three in the afternoon.
This is a linear game with very minor grouping elements. I wouldn’t call it a hard game, but it’s also the sort of game you should learn to do fast. If it takes you 8:30 to do the game, and you could have done it in 5:25, then you lost over three minutes you could have used for a harder game.
As with most modern games, there are no major upfront deductions. A couple of rules fit on the diagram directly. You should always draw rules directly on the diagram when possible; this makes the game more efficient. But beyond that there’s nothing to this game but knowing the rules and drawing them clearly.
Here’s the best way to draw the diagram:
Normally I don’t number my diagrams on my own page, but I do number them in explanations for clarity. However on this game I numbered the diagrams even on my own page, because the time slots are easy to forget. I’ll be adding a symbol to mark off morning/afternoon later.
Rather than draw the rules 1-by-1 in order, it’s best to read everything and draw things in the simplest order. For instance, Zane is mentioned in both rules 1 and 4: R is before Z, and Z is in the morning.
So you can combine these rules and put them both on the diagram. The vertical line in the middle separates morning and afternoon:
Note that I’ve also drawn the third rule: Tigay is in the afternoon. Also note that the fact that R – Z and T are floating above the diagram means that those variables must go in morning/afternoon, respectively, but that their placement isn’t fixed beyond that.
Also, I didn’t label anything “morning” or “afternoon”. Why bother? It should be obvious from the diagram as drawn where they are. And every extra detail will clutter your thinking and slow you down.
Only rule 2 is left: Wu is immediately before Yeaton. This can’t go on the diagram, so I just drew it to the right, also noting that S is random. These are the only three entertainers not on the diagram. The comma indicates they aren’t connected by any rules:
Normally I number the rules I can’t place on the diagram, but this time I found it clearer to indicate that “WY, S” are the only variables left to place on the diagram.
Note that it’s possible to make a major error on this game: incorrectly assuming that WY have to go in the afternoon. I made this error the first time, and some students I talked to also made it.
W can go in the morning, at 11 a.m. Then Y can go at 2 pm. Y is next after W, satisfying rule 2. The error depends on incorrectly assuming that WY can’t be separated by any length of time – but they can, as long as there’s no other entertainer between them.
Note that this is an example of an error that doesn’t have to cause a problem. As soon as I got to question 2 I saw that Wu could be scheduled in the morning (the question literally said so). So I drew a scenario for Wu in the morning (you’ll find it on question 2), saw that it was the only scenario with Wu in the morning, and finished the game without issue. I even finished quite quickly.
Everyone makes logic games errors, including me. The question is whether you know you will, and if you have plans to catch errors and recover from them if they happen.
I’ve written elsewhere about the benefits of repeating games, to solidify your intuition for deductions. Note that the purpose of repeating games is to prove the answers right, so it doesn’t matter if you remember the right answer.
I repeated this game about three days after I first saw it, by which time I had forgotten the answers. I’ve written how long it took me on the second attempt. That time, or a couple minutes above it, is roughly the standard you should be aspiring to – a lot of people take 8-9 minutes on a repeat attempt, get everything right, and pat themselves on the back. But that’s too slow. The faster you go when repeating, the faster you’ll learn to go the first time you see a game.
(I say “a couple minutes above” my time because, after years of teaching the LSAT, I’m really, really fast. You should be almost as fast as me, but you don’t exactly need to match my pace to score -0.)
Time on second attempt: 3:17
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