Good strategy for "if substituted for certain constraint"?

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Good strategy for "if substituted for certain constraint"?

Postby crazyvix » Fri Jan 31, 2014 3:45 am

Once in a while we might encounter question stems in LG like "Which one of the following, if substituted for the constraint that XXX, would have the same effect in determining XXX?"
This kind of question always gives me trouble, do you guys have any good strategy?


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Re: Good strategy for "if substituted for certain constraint"?

Postby BPlaura » Fri Jan 31, 2014 1:56 pm

Those types of questions can be really tricky. Keep in mind that your goal is twofold when you're replacing one of the rules:
(1) You want to maintain all of the original implications of the rule you're replacing, and
(2) You can't add any new implications or restrictions.

Sometimes, LSAC will make it pretty easy for you. For instance, for one of these questions (PT 57, Section 1, Game 1 - about the student doing chores on a Sunday, including "motorbike servicing" and "hedge trimming" - you know, typical student chores), there are two relevant rules. [I'm just going to use A, B & C here for ease of understanding.]

A must be immediately before or after B.
C must be after B.

The question asks you to replace the second rule. Fortunately, one of the answer choices says "C must be after A," which of course has the same effect!

So it is often worthwhile to take a quick look at the rule you're replacing and the other rules to see whether there are any obvious substitutions that would achieve the same effect.

Unfortunately, sometimes it's much more complicated than that (I'm looking at you, Jabrohn!). In those cases, you'll probably need to try out the answer choices. As soon as you realize that an answer choice is adding more limitations than the original rule, you can kick it out.

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