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- Tue Jun 21, 2011 1:46 pm
#88139
Setup and Rule Diagram Explanation
This is an Advanced Linear: Balanced game.
The game scenario presents a situation that at first appears relatively simple: a shuttle van makes four separate stops, and at each stop one of four passengers exits. This creates an Advanced Linear game that is Balanced:
This scenario is easy to understand, but the second and fourth rules contain language that makes this game much more challenging than it might first appear.
Rule #1. The first rule establishes that L must be the first or second stop:
Rule #2. Some students initially read this rule to mean that R exits when the shuttle reaches M (thus creating an RM vertical block). However, the language in the rule simply states that R is “still on board” when the van reaches M. This means that R can exit when the van reaches M, or it can exit after the van reaches M (and so no Not Laws can be drawn for this rule). The only possibility ruled out is R exiting the van prior to reaching M. Thus, the best diagram for this rule is:
Functionally, this rule is tough to track because once stop M is reached, R is not obligated to exit at that point, and can still exit at a later stop. However, there are some inferences that can be drawn from this rule. If R exits at the first stop, then M must be the first stop:
Similarly, if M is the last stop, R must exit at the last stop:
Rule #3. This rules creates a simple sequencing relationship between V and J:
Accordingly, V cannot be the last passenger to exit, and J cannot be the first passenger to exit, and we can create Not Laws reflecting those two facts:
Rule #4. This is the most challenging rule of the game. The first part of this sentence creates a conditional relationship that indicates that if J is still on board when the van reaches F, then G must still be on board when the van reaches S. One representation for this portion of the rule is:
Of course, the contrapositive for this portion would be:
The second portion of the rule indicates that if J is not still on board when the van reaches F (J
F), then G is not still on board when the van reaches S (G S), which can be diagrammed as:
By combining the contrapositive of the first portion with the diagram for the second portion, we arrive at:
This diagram means that the two conditions must always occur jointly. Conversely, if one of the two conditions does not occur, the other one will not occur either. In a nutshell, either both conditions happen, or both do not happen.
Because both the third and fourth rules contain J, an inference can be drawn linking J, albeit a tricky one. We will discuss this inference in the discussion for question #23.
The combination of the game scenario and four rules leads to the following final setup:
This is an Advanced Linear: Balanced game.
The game scenario presents a situation that at first appears relatively simple: a shuttle van makes four separate stops, and at each stop one of four passengers exits. This creates an Advanced Linear game that is Balanced:
This scenario is easy to understand, but the second and fourth rules contain language that makes this game much more challenging than it might first appear.
Rule #1. The first rule establishes that L must be the first or second stop:
Rule #2. Some students initially read this rule to mean that R exits when the shuttle reaches M (thus creating an RM vertical block). However, the language in the rule simply states that R is “still on board” when the van reaches M. This means that R can exit when the van reaches M, or it can exit after the van reaches M (and so no Not Laws can be drawn for this rule). The only possibility ruled out is R exiting the van prior to reaching M. Thus, the best diagram for this rule is:
Functionally, this rule is tough to track because once stop M is reached, R is not obligated to exit at that point, and can still exit at a later stop. However, there are some inferences that can be drawn from this rule. If R exits at the first stop, then M must be the first stop:
Similarly, if M is the last stop, R must exit at the last stop:
Rule #3. This rules creates a simple sequencing relationship between V and J:
Accordingly, V cannot be the last passenger to exit, and J cannot be the first passenger to exit, and we can create Not Laws reflecting those two facts:
Rule #4. This is the most challenging rule of the game. The first part of this sentence creates a conditional relationship that indicates that if J is still on board when the van reaches F, then G must still be on board when the van reaches S. One representation for this portion of the rule is:
Of course, the contrapositive for this portion would be:
The second portion of the rule indicates that if J is not still on board when the van reaches F (J
F), then G is not still on board when the van reaches S (G S), which can be diagrammed as:By combining the contrapositive of the first portion with the diagram for the second portion, we arrive at:
This diagram means that the two conditions must always occur jointly. Conversely, if one of the two conditions does not occur, the other one will not occur either. In a nutshell, either both conditions happen, or both do not happen.
Because both the third and fourth rules contain J, an inference can be drawn linking J, albeit a tricky one. We will discuss this inference in the discussion for question #23.
The combination of the game scenario and four rules leads to the following final setup:
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Dave Killoran
PowerScore Test Preparation
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PowerScore Test Preparation
Follow me on X/Twitter at http://twitter.com/DaveKilloran
My LSAT Articles: http://blog.powerscore.com/lsat/author/dave-killoran
PowerScore Podcast: http://www.powerscore.com/lsat/podcast/
If there is anyone who did this game before please explain.