This is the first logic game from Section II of LSAT 69, the June 2013 LSAT. There are six petri dishes which must be placed in a refrigerator. The dishes, labeled 1 through 6, must be placed on three shelves: the bottom shelf, the middle shelf, and the top shelf (B, M, T).
This is a grouping game. The first question of each game usually shows a good way to draw the diagram.
Here, though, the first question puts the bottom on the top, and the top on the bottom of the diagram. That’s confusing.
I reversed it, so that the bottom is on the bottom:
I’ve added the second rule to this diagram. 2 is always above 6. I drew it separately as well:
The first rule, I just memorized. There are at most three variables on a shelf. You could draw something like ‘3 MAX’ if it helps you remember.
Here are the third and fourth rules:
These boxes are like reversible suitcases. The order of the variables doesn’t matter. The boxes mean that 6 and 5 are always one group apart, and 1 and 4 are never in the same group.
Pay attention to the variables 1 and 4. They need two open groups. This is a three group game. Often, the questions will artificially fill one of the groups.
Then there will only be two groups left, and 1 and 4 must be split between those two groups.
The number 3 has no rules. I represent that by drawing a circle around 3:
A very small deduction
There’s one tiny deduction. Not even really a deduction, more of a fact. Since 6 and 5 go beside each other, one of them always has to be in the middle group.
Why? Well, they can be top and middle, or bottom and middle. Those are the only two possibilities. Here’s a drawing to help you visualize it:
So one of 5 or 6 is always in the middle. You can add this to the diagram if it helps you remember:
Of course, you won’t actually draw this 6/5 when making diagrams. Usually a question will place 5 or 6 anyway. This note on the main diagram is just a reminder, assuming you figured out the deduction in the first place.
Memorize the rules, if you can
And that’s it. There’s no magic in this game. No amazing deductions that will let you solve everything.
There are just three main rules. Remember them, and this game is easy. Forget them and it’s hard.
It’s possible to memorize those three rules without much difficulty. The key is not rushing to start the questions. Spend some time on the setup.
I always read the rules once before drawing anything. I read them again while I draw. I read them once more to make sure I made no mistakes. Finally, I read them again to eliminate answers on the first question.
So I read the rules four times. This process might take me 20 seconds more than someone who reads the rules 1-2 times. You read faster each time you reread.
It is worth it. I can almost always memorize the rules effortlessly by doing this.
I mean c’mon, the rules are just a few facts. Read them four times, and you’d remember most of the rules too. So why don’t you?
I guarantee you’ll go much faster through the questions when you memorize the rules. And make less mistakes. All from 20 seconds more reading.
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