This is an explanation of the third logic game from Section IV of LSAT preptest 34, the June 2001 LSAT.
Seven trains arrive at Middlebrook Station on Saturday. The trains are: Quigley, Rockville, Sunnydale, Tilbury, Victoria, Wooster, and York (Q, R, S, T, V, W, Y). The rules allow you to determine what orders the trains can arrive in.
This is another linear game. They’re my favorite type. I like this game in particular because the game can be split into two clear scenarios that let you deduce a lot.
The seven trains arrive one at a time. This is the same seven-slotted setup you’ll find on so many logic games.
The first rule immediately lets us split this into two scenarios. You should always draw two scenarios when a rule this clearly divides the game.
You might wonder why you should make two separate diagrams. The rule itself is obvious, and it seems like a lot of work to make more drawings.
Well, it lets you more easily visualize the game. And there are usually many deductions unique to each diagram. The second rule has different effects in each scenario.
In the first scenario, the W-S-Y ordering goes before 4. In the second scenario, it goes after 4.
The next rule is just straightforward sequencing.
But it becomes a bit more interesting when we add in the fact that T can’t go beside V. Here’s how I draw that type of rule:
Pretend that box is a suitcase. Imagine you can pick it up by the handle and flip it around. You can’t have either TV or VT.
So T and V come after R and they can’t come beside each other.
Q is our only random variable: it has no rules attached to it.
Putting It All Together
You should never move onto the questions without at least trying to combine rules. It’s true that on some games there aren’t many deductions. But on many games you can make some very important deductions that strictly limit what can be true.
This game is like that.
Take a look at our first scenario:
Where can you put R, T and V? R has to go before them.
If you put R in 5, then T and V will be in 6 and 7…beside each other. That doesn’t work. And there’s no space for T or V to go before Y.
You need to put T and V in 5 and 7. R will go in front of Y somewhere, along with W and S. And there’s only one spot left for Q, in slot 6.
The end result looks like this:
I placed the first three variables overhead to indicate that they go in the first three slots, but I don’t know where. I use the comma between R and W-S to indicate that R is in the same region as W and S, but I have no idea where it is in relation to them.
We know the first three variables are before Y, and W is before S. That’s all.
You don’t have to draw R, “W –S “ the same way I did. It makes sense to me, but you might think of some other method that makes more sense for you.
But make sure you represent it somehow. If you don’t draw a deduction, there’s a good chance you’ll forget it. Even I forget if I don’t draw my deductions.)
The T/V and V/T mean that one of them goes in 5 and the other goes in 7.
The second scenario is similarly restricted. Take a look and try to think about where you can put R, T and V. Remember, R goes before V and T, and V and T aren’t beside each other:
Did you figure it out? There is only one space free after W, and one of T/V has to go there.
If you put R, T and V in spots 1-2-3, T and V will be beside each other. So one of T/V goes with S-Y after W.
That leaves R, the other V/T and Q to go before W. It looks like this.
The variables are placed overhead to indicate which region they go in. The commas show that Q can go before or after (or in between) R-V/T.
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