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- Fri Nov 23, 2012 12:56 pm
#92241
Setup and Rule Diagram Explanation
This is an Advanced Linear: Balanced, Identify the Possibilities game.
This is a challenging game made considerably easier by applying the right technique, which, in this case, is to identify each of the possibilities. Some of the “hardest” games on the LSAT are best attacked with this technique, and once the correct technique is applied, the game no longer seems as difficult. An examination of all LSAT games makes it clear that the test makers expect you to have the ability to identify “limited solution set” scenarios when they occur. In this game, there are a large number of rules, and so it is not surprising that there would be some powerful inferences. Let’s look at each rule and develop the case for showing the possibilities.
The basic structure of the game from the scenario is as follows:
The first rule establishes that J and K are on the same team. Normally this would be a represented as a vertical JK block, but the second and fourth rules establish that K and N are on different teams, and that N is on team Y (along with M). Thus, accounting for the interaction of the first, second, and fourth rules, J and K are on team X, and N and M are on team Y:
The third rule indicates that R runs in an earlier leg than P:
From this rule, we can infer that R can never run the fourth leg, and P can never run the first leg:
The fifth rule establishes two more Not Laws, this time for J and M on the third leg:
The sixth rule stipulates that K and L run second. We have already established that K is on team X, so L must be on team Y:
The seventh and final rule indicates that O runs fourth:
At this point, most students continue on to the questions. But, there are more inferences to be made, and these inferences come from examining the most restricted open spot on the diagram: the third leg. From the fifth rule, the third leg cannot be run by J or M. But, because of the other rules, we can also eliminate K, L, and O from running third. Thus, J, M, K, L, and O cannot run the third leg, leaving only N, P, and R available to run third. But, from the third rule, R must run an earlier leg than P, which means that both P and R cannot run third simultaneously. By Hurdling the Uncertainty then, we can infer that N must run third. And, from the fourth rule, we know that N is on team Y. Thus, N must run third for team Y, and P or R must run third for team X:
That N must run third for team Y is the key inference of the game, and it destroys questions #21, #22, and #23.
While making the inference that N is third is critical for success in this game, there are additional inferences to be made, namely on the first leg. From the third rule, P can never run first, and from the other inferences and rules K, L, M, and O can also be eliminated from running first. With those five people eliminated, only J, M, and R can run the first leg. As J is on team X and M is on team Y, we can infer that J or R must run first for team X, and M or R must run first for team Y.
In evaluating this setup, three of the people are placed, and every other position has either a dual-option or split-option. Clearly, the game has significant inherent limitations, which suggests that the best approach is to Identify the Possibilities.
There are four possibilities: two when O is on team X, and two when O is on team Y:
Possibility #1: O on Team X, P runs the third leg
When O is on team X and P runs the third leg on team X, then J must run the first leg on team X (that is the only available space on team X for J) and R must run the first leg on team Y, forcing M to run the fourth leg on team Y:
Possibility #2: O on Team X, P runs the fourth leg
When O is on team X and P runs the fourth leg on team Y, then R must run the third leg on team X. J must run the first leg on team X and M must run the first leg on team Y:
Possibility #3: O on Team Y, P runs the third leg
When O is on team Y and P runs the third leg on team X, then M must run the first leg on team Y (that is the only available space on team Y for M). R must then run the first leg on team X, and J must run the fourth leg on team X:
Possibility #4: O on Team Y, P runs the fourth leg
When O is on team Y and P runs the fourth leg on team X, then M must run the first leg on team Y (that is the only available space on team Y for M). R must then run the third leg on team X, and J must run the first leg on team X:
With these four possibilities in hand, the questions can be solved quickly.
This is an Advanced Linear: Balanced, Identify the Possibilities game.
This is a challenging game made considerably easier by applying the right technique, which, in this case, is to identify each of the possibilities. Some of the “hardest” games on the LSAT are best attacked with this technique, and once the correct technique is applied, the game no longer seems as difficult. An examination of all LSAT games makes it clear that the test makers expect you to have the ability to identify “limited solution set” scenarios when they occur. In this game, there are a large number of rules, and so it is not surprising that there would be some powerful inferences. Let’s look at each rule and develop the case for showing the possibilities.
The basic structure of the game from the scenario is as follows:
The first rule establishes that J and K are on the same team. Normally this would be a represented as a vertical JK block, but the second and fourth rules establish that K and N are on different teams, and that N is on team Y (along with M). Thus, accounting for the interaction of the first, second, and fourth rules, J and K are on team X, and N and M are on team Y:
The third rule indicates that R runs in an earlier leg than P:
From this rule, we can infer that R can never run the fourth leg, and P can never run the first leg:
The fifth rule establishes two more Not Laws, this time for J and M on the third leg:
The sixth rule stipulates that K and L run second. We have already established that K is on team X, so L must be on team Y:
The seventh and final rule indicates that O runs fourth:
At this point, most students continue on to the questions. But, there are more inferences to be made, and these inferences come from examining the most restricted open spot on the diagram: the third leg. From the fifth rule, the third leg cannot be run by J or M. But, because of the other rules, we can also eliminate K, L, and O from running third. Thus, J, M, K, L, and O cannot run the third leg, leaving only N, P, and R available to run third. But, from the third rule, R must run an earlier leg than P, which means that both P and R cannot run third simultaneously. By Hurdling the Uncertainty then, we can infer that N must run third. And, from the fourth rule, we know that N is on team Y. Thus, N must run third for team Y, and P or R must run third for team X:
That N must run third for team Y is the key inference of the game, and it destroys questions #21, #22, and #23.
While making the inference that N is third is critical for success in this game, there are additional inferences to be made, namely on the first leg. From the third rule, P can never run first, and from the other inferences and rules K, L, M, and O can also be eliminated from running first. With those five people eliminated, only J, M, and R can run the first leg. As J is on team X and M is on team Y, we can infer that J or R must run first for team X, and M or R must run first for team Y.
In evaluating this setup, three of the people are placed, and every other position has either a dual-option or split-option. Clearly, the game has significant inherent limitations, which suggests that the best approach is to Identify the Possibilities.
There are four possibilities: two when O is on team X, and two when O is on team Y:
Possibility #1: O on Team X, P runs the third leg
When O is on team X and P runs the third leg on team X, then J must run the first leg on team X (that is the only available space on team X for J) and R must run the first leg on team Y, forcing M to run the fourth leg on team Y:
Possibility #2: O on Team X, P runs the fourth leg
When O is on team X and P runs the fourth leg on team Y, then R must run the third leg on team X. J must run the first leg on team X and M must run the first leg on team Y:
Possibility #3: O on Team Y, P runs the third leg
When O is on team Y and P runs the third leg on team X, then M must run the first leg on team Y (that is the only available space on team Y for M). R must then run the first leg on team X, and J must run the fourth leg on team X:
Possibility #4: O on Team Y, P runs the fourth leg
When O is on team Y and P runs the fourth leg on team X, then M must run the first leg on team Y (that is the only available space on team Y for M). R must then run the third leg on team X, and J must run the first leg on team X:
With these four possibilities in hand, the questions can be solved quickly.
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Dave Killoran
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/
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/
