June 2007 LSAT, Game 3 Setup

Onward with the most learnable section of the LSAT--the Logic Games. Take a couple deep breaths if this section is currently causing you panic. Everyone can improve on this section. Yes, it's the most frequently tanked section. But it's also the most frequently crushed section. I recently had a student get three questions correct on the Logic Games on her first diagnostic LSAT--and by the end of the 8-week class, the student was scoring perfectly (22 to 24 questions correct). It's simply not possible to improve by 20 points on any other section. It'll take some practice, but the payoff will be huge. We can do this. Also: Don't try to run before you can walk. The earlier games in any section tend to be the easier games. So before you tackle Game 3, you probably want to make sure you understand Game 1 and Game 2.

Questions 11-17 of the  June 2007 LSAT deal with a voyage on a cruise ship. The ship's going to make seven stops, at some combination of four destinations (G, J, M, and T.) Here are the rules:

  • Each destination must be used at least once. (This rule is hidden within the paragraph part of the game, rather than in the indented "rules" section. But it's a rule nonetheless--watch out for this, it's a very common trick.
  • J can't be fourth.
  • T is always seventh.
  • M must be used exactly twice.
  • There must be at least one G in between the two stops at M.
  • G precedes every trip to J.
  • No consecutive stops at any destination.

What's the chink in the armor here? What stop is the hardest to schedule? If you were scheduling the voyages, which destination would worry you the most?

Personally, I'm worried about J. The reason I'm worried about J is that it's mentioned in two rules, and it's a pain in the ass in both of them. It can't be fourth, and it has to always be preceded by G. So there might only be a couple ways to fit J in. Let's see:

J can't be first.  (Because if J was first then G would have to go before that, and there's no spot before the first spot.)

If J went second, then G would have to go first.

If J went third, then G would have to go second.

J can't go fourth, because there's a rule about that.

If J goes fifth, then G would have to go fourth.

If J goes sixth, then G would have to go fifth.

J can't go seventh, because that spot is already taken by T.

So, as it turns out, there are four places for J:  Second, third, fifth, or sixth. Interestingly (and perhaps usefully), the second and fifth spots end up very restricted. It must be true that either the second or the fifth spot (or both) is taken up by either J or G. Look:

G  J  __  __  __  __  T

or

__ G  J  __  __  __  T

or

__  __  __  G  J  __  T

or

__  __  __  __  G  J  T

In each of these scenarios, either the second or the fifth spot is occupied by either G or J. (And note that it's possible to occupy both the second and fifth spot with G/J. But at a minimum, one of these spots has to be G or J.)

I've done this game a million times, and I've never done it exactly this way before. I'm not 100% sure I'm doing it the best possible way. But that's fine! Don't let the perfect be the enemy of the good. It's not possible to always do every game in the exact optimal fashion. Every game is a little bit different. Focus on writing down things you know for sure. Here, I have learned for sure that there are only four spots for J, and that the second or fifth spot (or both) must be taken up by either G or J. I don't know if I'm going to crush this game, but I am confident that I haven't totally effed it up at this point. I don't see any major brilliant inferences remaining, so it feels like it's time to go on to the questions. See you in the next post.