Everyone hates rule substitution questions, and this is the second on this section. Ouch.
I actually find rule substitution questions very easy. I’ll try to convince you this is possible. There are two things a substituted rule must do:
- Allow everything allowed by the old rule.
- Ban everything not allowed by the old rule.
This gives you an easy way to eliminate answers. A, B and E add extra restrictions.
- A: This says T is discussed third. That doesn’t normally have to be true. Wrong answer!
- B: This says T is discussed earlier than F. Not a normal restriction. Eliminate!
- E: This says F is discussed third. Normally, F can also go 1st or 2nd. Bad answer!
Have the courage of your convictions. Rule substitution answers are full of silly restrictions. If a restriction contradicts the normal rules, eliminate that answer.
Now we are left with C and D. The second part of my guidelines says that rules have to ban everything that’s normally not allowed.
C doesn’t do this. C says that K and R have to be among the last three. I’m sorry, but K and R have to among the last two. This answer seems too broad. Let’s look at D.
When I did this question, I went right to D because it said O has to be fourth. That’s the most important deduction in the game, and it’s also a consequence of the rule we’re replacing.
Rule substitution answers usually work by describing a consequence of the rule we’re replacing. D does describe a consequence of the rule (O is fourth), so this is very promising. Now let’s see where this leaves us. O is fourth, and we know from rule 3 that N and T have to be before O.
This diagram shows what we’ve deduced so far.
We still have to place F and KR. This answer says that KR are beside each other and reversible. So they need two spaces.
The only two spaces open are 5 and 6. That means KR goes there, and F has to go before O. So this exactly matches our original setup. D is CORRECT.
I didn’t prove this answer with this degree of certainty on the test. I just eliminated A, B and E like I showed you.
Then I discarded C because it said “last three”, and I picked D because it placed O fourth. I did do a quick mental check that the rest of the rule worked, but those were the main elements I used to quickly arrive at the answer.
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MemberDan Rosenthal says
For PT 71 S2 Q16, choice D is the correct choice, but the reason given for discarding choice C is not correct. The original rules restrict K and R to be in the last two, and this means they ARE in the last three as well. (Aren’t they all in the last six?) The real reason choice C is invalid is because we can falsify the original rule and maintain the new rule: NTFKOR. Now, the original rule is false because O is not before K. But the new rule is true because F is in the first three and K and R are in the last three. Did I miss something?
Daniel says
Hi Graeme,
Thanks a bunch for your website! As a student of modest means looking to do as well as I can on the LSAT, I can’t express how valuable a resource it is and has been for me. I recently took the June LSAT and have my sights set on retaking. I’ve discovered that Rule Equivalence questions and I don’t get along too well! I completed question #5 of PT 63 (June ’11) yesterday, and although I actually got the answered it correctly, I was hoping to get some advice on how to attack these types more efficiently and effectively. Please help.
Daniel
FounderGraeme Blake says
Thanks, glad you like them! Do you mean rule substitution?
Search this on google:
site:lsathacks.com rule substitution
That will find all the pages where I explain that type of question. You’ll learn about how to approach them by doing the games and reading those explanations.
For anyone reading this comment who can’t copy paste what I typed, you can click on this link to search my site for rule substitution: http://lmgtfy.com/?q=site%3Alsathacks.com+rule+substitution
(lmgtfy is normally used to insult people, but that’s not my intent here. What I wrote above is a rare search, so clicking that link is the easiest way to make sure the search works for you. Good luck with rule substitution, they’re very learnable!)