This is an explanation of the third logic game from Section III of LSAT Preptest 66, the June 2012 LSAT.
A software company employs seven sales representatives: Kim, Mahr, Parra, Quinn, Stuckey, Tiao, and Udall (K, M, P, Q, S, T, U). Each of them will be assigned in exactly one of the three sales zones: Zone 1, Zone 2 and Zone 3 (1, 2, 3).
Setup
This is a grouping game. There are no ordering elements.
The game has five rules, which is more than most games. It will be important to simplify these and keep a clear list of rules.
I’ve drawn the three groups vertical, as the game itself did in question 12. You can also draw this game horizontally. These differences are just a matter of personal preference.
I’ve drawn two spots in group 3, as a reminder of the final rule. You should always read all the rules before drawing, it lets you take shortcuts like this.
The final rule says Group 3 always has more representatives than group 2 does. You can draw something like this as a further reminder on your list of rules:
But this diagram isn’t that helpful. 3 > 2 is sort of ambiguous. It looks like a mathematical equation, referring to the numbers 3 and 2.
In the heat of the moment, it’s easy to forget that this actually refers to the numbers of reps in groups 3 and 2.
It’s far better just to memorize rules that have no clear diagram. When a game gives you a unique situation, make up a plausible diagram and try to memorize it.
The first and second rules I also prefer to memorize, or partially memorize. They say we need one of two variables in a group, but not both.
This means that, for example, exactly one of P or T will be in group 1. But both of them can’t be there.
I like drawing this directly on the main diagram:
There’s no great way to draw a ‘either-or but not both’ rule. I usually draw them like this:
These are actually ‘at least one’ diagrams. I memorize the added context that you can’t have both at once.
It’s true that the diagram leaves out some information, but you can still solve a game very effectively with an imperfect diagram. Memorizing the missing elements is easier than it sounds, and a very powerful tool.
If you want to capture the full effect of the rules, you can draw these diagrams. These are just for the first rule:
This means that T1 is always NOT with P1, and the reverse. If T is not in 1, P is there.
That diagram is accurate, and if you memorize what it means, it works. But it’s big and clunky. For rare situations, I prefer a smaller diagram, and keeping part of the rule in my head.
Ok, the last two rules are simple. PQ and SU go together.
You should also note the random variables. There are two, M and K:
That’s all the rules. There aren’t any deductions, but you can turn the rules into scenarios.
Scenarios are not essential to solve this game, but the though process involved in making scenarios is very useful.
I didn’t make scenarios when I first did this game, but I could construct them on the fly when doing questions because I’m used to doing it. I’ve built scenarios a bit further on as an example. You should follow along and draw them yourself if you’re not clear how to do it on your own.
Before you try this game, make sure you’ve memorized the full impact of rules 1 and 2. There’s no diagram that will be as effective as having them in your head.
There are no shortcuts on logic games. This section tests your working memory. To get better, you have to be comfortable with memorizing at least a couple of the rules.
Want a free Logic Games lesson?
Get a free sample of the Logic Games Mastery Seminar. Learn tips for going faster at logic games
Yitz says
Oops. One more question, since I often make the wrong assumption that all spots have to be used or all players have to be used when the question doesn’t say that.
Do I understand the question correctly to mean that there doesn’t need to be anybody in zone 3, (but that would be an inference since zone 3 has to have more than zone 2 and zone 2 is guaranteed going to have at least 1 sales rep)?
FounderGraeme Blake says
>Do I understand the question correctly to mean that there doesn’t need to be anybody in zone 3
No, because of the final rule. There must be somebody in zone 3. And at least two, because rule two says there’s at least one person in zone 2.
So this game originally doesn’t require someone in each zone, but in practice the rules mean the minimums are 1, 1 and 2.
Yitz says
You said there are no inferences, but doesn’t rule 1 + rule 3 mean that zone 1 is PQ or T and also that T&Q can’t be together?
Same deal with rules 2 & 4 and their impact on SU or T + T&U can’t be together?
And therefore also a pretty big inference that T can’t be with U, S, P or Q?
Have I over-inferred something?
FounderGraeme Blake says
Those are true inferences. I’m not sure they’re practical though. They sort of flow naturally from the rules as drawn.
Meaning that if a question places P in group 1, and you know the rules, you should see that Q goes in group one and that T doesn’t.
It’s a personal preference whether or not to write those down. Since I know the rules, I know I’ll see them, and I’d get confused if I wrote down everything that was true as a consequence of rules.
I tend to stick to “must be true” situations when making deductions. As in things that are always true in every scenario and I can draw on the diagram. Your deductions are always true, but they can’t be drawn because they only happen IF something else happens.