LSAT 90, Logic Game 2, Question 11, LSATHacks

For rule substitution questions, the key is to figure out what the rule that is being replaced does in terms of restrictions and shaping the diagrams. Let’s have a close look at the game board. Where could J and G even intersect?:

• Not group 1: G can’t go there. (rule 1)
• Not group 3: J can’t go there. (rule 2)

So J and G could only even possibly be placed together in group 2:

Therefore, we could replace the rule by focussing on group 2 and forcing J or G out of there when one is in.

B does that, and B is CORRECT. It says that if J is second, G must go third (i.e. not in group 1, and not in group 2 with J). This new rule makes it impossible for G and J to be together anywhere: rule 1 prevents overlap in group 1, the new rule overlap in group 2, and rule 3 prevents overlap in group 3.

Another possible correct answer would have been the inverse of this: If G is placed in group 2, J must go in group 1.

And that’s it! Rule substitution questions can really be this simple. Remember, LSAC isn’t working with many tools here. They have to use the remaining rules and restrictions in order to replace the rule. So by careful study of the existing game, you can figure out how they must do the replacement. It’s all about looking at the other restrictions and seeing how they interact with the variables in question.

Alternate Approach: Process of Elimination

You can also do process of elimination. The other answers will allow things that shouldn’t be allowed (i.e. G and J together somewhere) or forbid things that should be allowed. This process of elimination is slower, but still viable if you can’t figure out the structure. And the structure may come to you as you eliminate.

Two tips to speed up your process of elimination:

1. There are now only three rules, in addition to the answer choice’s rule: FG not in first, JL not in third, F must be with G/H
2. Remember that you are trying to do one of two things: 1. make a working scenario, which obeys the rule in the answer, but yet puts G and J together in group 2, or 2. Show that the rule forbids a scenario that should apply.

So to show G and J being together despite the rule, start with GJ in group 2 and see if you can still do the rule.

If you can’t, instead, start with the rule, then see if it blocks you from making a diagram that obeys the other three rules. This is the most common way for answers to be wrong: new rules commonly forbid scenarios that obey all the old rules.

A is wrong because it allows G and J to go together if H is in the third group:

C is wrong because it forbids this scenario which normally should be allowed. To disprove this answer you have to put J and F far apart. So I put J first and F last, and checked if I could make a working scenario.  You normally can:

D is wrong because it forbids this scenario which should normally be allowed. To disprove this answer you have to put J and G far apart. So I put J first, G last, and checked if I could make a working scenario that obeyed the rules:

I found E tempting, because I thought J and L were interchangeable. Doesn’t this answer produce the same effect? Sort of: this answer makes L the new J, and with this rule L behaved exactly as J did before. But, that isn’t what we’re trying to do. We’re trying to forbid J and G from being together! And with this rule, they can be, as in this scenario:

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