Linear Setup Practice Drill #6

[beniakc]

A college dorm manager must assign five students ---p,q,r,s,t, to 5 different floors in the dorm. the floors are 1, 2, 3, 5, and 6 (notice no 4). assignment must comply with the following:
p must be directly above q = PQ boxed
r must be assigned to floor 6

explain this to me. The answer in the book pg 3-109 says to add floor #4 but XXX it out. This limits the location of PQ. Why are we supposed to add a floor that is not in the question??

[Dave Killoran]

Hey Beniakc,

Thanks for the great question! The idea behind this drill problem reflects something that appeared on the LSAT previously. Namely, there was a game where Law Services talked about days of the week, and then "dropped" one of the days when they began scheduling variables for the days. There was then a rule based variables being on consecutive days, and huge numbers of people got killed on the game because when they made their diagrams, they didn't include the "missing" day (and hence they didn't realize that certain days weren't consecutive).

The idea is similar in this drill. While Floor 4 "exists," it isn't used by the variables. This directly impacts P and Q as they are in a relationship where floor positioning matters (and then P can't go on floor 5 and Q can't go on floor 3).

The broader principle to derive is to examine the way the scenario presents the options--is something missing that might affect variable placement? If so, show it on your diagram, but indicate that it is unavailable by using Xs or just scratching it out.

Please let me know if that helps. Thanks!

[beniakc]

I understand what your saying, but it makes no sence to me. Consider the following. If we had a similar question involving floors of a hotel (we'll say floors 10-15). Are we to "assume" that since some (not all) hotels won't use e number 13 that we shouldn't include that floor in our solution or diagram? Or would we?

[Adam Tyson]

Beniakc,

The issue here isn't that there IS no 4th floor, but that none of our students can be assigned to it, so for our purposes it's an empty floor. By including it and then blocking it out, it will help prevent you from mistakenly placing P on 5 and Q on 3 (which would violate the rule that P must be on a floor directly above Q). Which, by the way, is exactly the mistake they want you to make, and the whole reason why they left out that floor. Once you include the 4th floor and block it out, the the PQ block can only go on either 1 and 2 or 2 and 3.

FYI, in your example of floors 10-15 of a hotel, if you ever did get a question like that on the LSAT, you should NOT assume there is no 13th floor unless the rules tell you so. That could make for a very clever trap by the authors, too. If there were no 13th floor, then P could be on 14 and be directly above Q on 12, and the rules wouldn't be violated. Remember not to assume anything - they tell you what you need to know, and if there's something vague it's because they want to trap you. Beware of missing floors!

Good luck,

Adam

[Dave Killoran]

I'll second what Adam said, and also add that Law Services would never create a "13th floor" scenario for the exact reason you specify. But, they might easily make another game with hours of the day, days of the week, or months of the year, and create the same type of trap. The point is to be vigilant and to not assume that non-availability means non-existence.

Please let me know if that helps. Thanks!

[beniakc]

Dave,
What you said makes more sence. So to clarify, if a similar question popped up using months, (jan-June), we should logically assume that jan, feb, mar, apr, may and june would all be considered in the problem regardless if they are listed as possibilities.

[Dave Killoran]

That is 100% correct