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This is a Logic Games question from June 1996.
As always (unless the answer is obvious based on the rules, which is not the case here), we will make a diagram consisting of a table with symbols in it. These diagrams work for, I would estimate, 99% of games. I've taken every test ever released, and I've seen perhaps two where diagrams don't help.
So, what should our table look like? Make the days your base and represent the workshops with symbols (L for Lighting, etc). Something like:
Monday:
Tues:
Wed:
Thurs:
Fri:
Our goal with the diagram is to find an arrangement of symbols in compliance with the diagram that eliminates as many choices as possible. Many choices we make will be arbitrary - we just want some set-up that follows the rules.
When we make the diagram, we want to violate as many choices as possible. This means we should do what the choice says, in order to show it doesn't have to be false, so we can eliminate it.
P must go on Thurs and Fri because the question says "must be consecutive." We don't see a way to put L on Tues and Wed, since that would push R to Thurs and Fri, and Fri must be kept clear for P alone. So, we'll put L and Mon and Tues:
Monday: L
Tues: L
Wed:
Thurs: P
Fri: P
Now, the only place for R is Wed and Thurs, since it must be after L, but it cannot go on Fri. To violate choice D, we'll put S on the same days as L, Mon and Tues:
Monday: L S
Tues: L S
Wed: R
Thurs: P R
Fri: P
We now have a valid diagram. If a choice is true in this diagram, it can't be the right answer, since it need not be false. If it doesn't appear in the diagram, we can't eliminate it.
A) Can't eliminate
B) Eliminated
C) Eliminated
D) Eliminated
E) Can't eliminate
Now, we need to alter our diagram because we have two answers remaining. We see no way to move L to eliminate choice A...if we did that, it wouldn't be before R and P (neither of which can be moved, by the rules). So let's try to eliminate choice E. We'll just move S down to Tues and Wed:
Monday: L
Tues: L S
Wed: R S
Thurs: P R
Fri: P
E's out and A is correct.
Remember:
1) Make a diagram with symbols in a table unless the answer can be easily deduced from the rules without one.
2) Violate choices when you can when you make a diagram. Do things in the diagram, on purpose, that will eliminate answer choices. However, don't get too hung up on this. The main goal is to make the diagram, not to sit around all day agonizing over it. You can always alter it later, as we did, to eliminate more choices.
3) In a question asking you what "must be false," you eliminate choices by showing that they could be true. We did that here by doing whatever the choice said (like putting S with R) in the diagram, to prove it could be done.
I know this question was tougher than most, but with practice, you can do one of these questions easily. If you have questions, post a comment.
Just browsing around, and wondering what advice was being given to students about games. You get to the right answer fine, but I'd like to offer how I'd set it up. (Nothing personal of course.) My advice is to take as much information out of the rules as possible first, make that into a diagram (in this case a table) before even looking at the question's conditions and question.
ReplyDeleteFor this problem, that would involve first combining rule 1 & 3 to realize that P & R can never take place Monday or Tuesday (because it must be after L), and that L can never be Thursday or Friday.
I'd like to draw this up, but unfortunately the comments section won't allow tables, non-breaking spaces, underlining, or tabs... so I can't get anything to line up right in HTML. So you'll just have to use your imagination (or a pencil, if you wanna go really low tech).
Basically along the top of my column I'd have the days (M, T, W, R, F) with rows labeled (L, P, R, S) with X's marking out row L:R & F; row P: M & T; and row R: M & T.
I would then fill in an "O" where an answer must go. For instance, because Lighting is either on (Monday and Tuesday) or on (Tuesday and Wednesday) it must be on Tuesday. These would be L: Tues, and R & S: Thurs.
Now you have a diagram that not only makes Q11 a snap, but will probably be helpful on 8, 9, 10 & 12 as well. If it's as short & simple as this diagram I'd be tempted to circle it & rewrite it for each Q before I tarnished it with question specific conditionals.
Maybe that's what you're trying to show but had trouble with tables as well. At any rate, my point is that it's essential to build a diagram & make all deductions (e.g. Rehearsals must be on Thursdays) before adding conditions specific to a question (Production is the only class on Friday). While you may have gotten the answer quicker, the user of such a method may have a harder time taking the answer/process from this question and using it on the rest in this section.
Alright, maybe I made things less clear to your readers, but that's my advice. Do with it what you will.
--Dante
I also found that by setting up a diagram with what must exist as a master diagram and then filling in what could exist based on the conditions of the question allowed me to eliminate the wrong answeres very quickly.
ReplyDeleteThanks, guys! Both of your diagrams really helped. These questions are really hard for me and I am a visual person, so I have been trying to develop a table that works well.
ReplyDeleteWhat did the first rule mean? Did we do that? "The two days on which a given workshop is in session are consecutive"
ReplyDelete