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Course: LSAT > Unit 1
Lesson 5: Analytical Reasoning – Worked examples- Ordering setup | Overview | Rules and deductions
- Ordering setup | Given info–basic 1 | Worked example
- Ordering setup | Given info–basic 2 | Worked example
- Ordering setup | Given info–could be true | Worked example
- Ordering setup | Given info–cannot be true 1 | Worked example
- Ordering setup | Given info–cannot be true 2 | Worked example
- Ordering setup | Given info–must be true | Worked example
- Ordering setup | New info–could be true 1 | Worked example
- Ordering setup | New info–could be true 2 | Worked example
- Ordering setup | New info–could be true 3 | Worked example
- Ordering setup | Completely determines | Worked example
- Ordering setup | New info-must be true | Worked example
- Grouping setup | Overview | Rules and deductions
- Grouping setup | Given info–basic | Worked example
- Grouping setup | Given info–could be true | Worked example
- Grouping setup | Given info–must be false | Worked example
- Grouping setup | Given info–must be true 1 | Worked example
- Grouping setup | Given info–must be true 2 | Worked example
- Grouping setup | New info–could be true 1 | Worked example
- Grouping setup | New info–could be true 2 | Worked example
- Grouping setup | New info–must be true | Worked example
- Grouping setup | "Completely determines" | Worked example
- Mixed setup | Overview | Rules and deductions
- Mixed setup | Given info–basic | Worked example
- Mixed setup | Given info–could be true 1 | Worked example
- Mixed setup | Given info–could be true 2 | Worked example
- Mixed setup | Given info–must be true | Worked example
- Mixed setup | Given info–cannot be true | Worked example
- Mixed setup | New info–could be true | Worked example
- Mixed setup | New info–must be true 1 | Worked example
- Mixed setup | New info–must be true 2 | Worked example
- Mixed setup | Rule substitution | Worked example
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Grouping setup | Overview | Rules and deductions
Watch a demonstration of how to approach a grouping setup on the analytical reasoning section of the LSAT.
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The explanation here does not make any sense. There is no rule that says red cannot be paired with yellow. And I don't understand why the second and third costume color combination cannot have red. The explanation here is so vague.(3 votes)- The rules indicate that yellow must always be paired with indigo. Since red cannot be paired with indigo but yellow must always be paired with indigo red cannot be paired with yellow. Imagine designing a costume that has red, yellow in it. Looking back at the rules we see that since there is yellow there needs to be indigo in it as well. But this contradicts the rule that red cannot be with indigo. This means that if a costume with three colours has red, by process of elimination we must have orange and white because no other colour fits. Therefore red only has one possible colour combination and order doesn't matter so ROW, RWO, WOR, etc are not different pairings. Since red has only one pairing and there can be no repeat pairings the other pairings cannot have red in them.(12 votes)
- The last rule seems to be misunderstood. @2:12. If R then ~I AND ~G. The instructor had If R then ~I or ~G.(2 votes)
I think the or actually does make sense because if I AND G weren't possible, that would imply that just one of those letters by themselves could work. By saying or it shows that there is no circumstance where either of the letters could be used.(1 vote)
2:12Video transcript
- [Instructor] This setup has to do with the colors of three costumes. First we'll want to look
at the basic structure of the setup so we can understand what type of questions these are and how we might
represent it in a diagram. Here's what the setup says: "A costume designer has
been asked to put together "exactly three tricolored costumes, "choosing among six
colors - green, indigo, "orange, red, white, and yellow. "Each of the six colors must appear "in at least one of the costumes. "The costumes are to be designed according "to the following requirements." Before we look at the requirements, let's think about what this tell us. The setup asks us to group six
colors among three costumes and there's nothing in
the setup to suggest that the order of the costumes matter, so it looks like this is a straightforward grouping scenario. What information do we have? Well, a designer is putting together three tri-colored costumes, so three costumes of three colors each, so here's one way we might represent that. There are three sets of three. And if we want to label
these one, two, and three, we can but just don't get confused. The order doesn't matter but let's think, there are three costumes
of three colors each. We know that there are six colors, green, indigo, orange, red, white, and yellow. Now let's look at the requirements. "No two costumes can have
the same color combination." There isn't a great way to
represent this in the diagram so maybe let's just
make a note to ourselves saying something like, "All different," just so we'd remember that. Okay, "any costume that has indigo in it "must also have yellow in it." So indigo, then it's got yellow in it. "Any costume that has yellow in it "must also have indigo in it," so we can just add this here. Indigo, then it has yellow in it and if it has yellow in it,
then it has indigo in it. "If a costume has red in it, "then it can have
neither indigo or green." So if it's got red in it, then it doesn't have either of these, not indigo or green. Okay, let's see if we can
make any inferences from this. Well, if any costume with
indigo must have yellow and any costume with
yellow must have indigo, this is another way of saying that indigo and yellow are a pair. So this might be an
easier way of remembering that indigo and yellow are a pair. So let's erase this, just so we can see that
these two always go together. The fourth rule says
that red can't be paired with either indigo or green. Since indigo and yellow are a pair, this also means that red
can't be paired with yellow. So you could write this. Say it like this. Since there are only six colors though, this means that the only colors left that could be with red are white or orange and each costume is three colors. So if there are only two colors left that could be with red, white and orange, this means that one of the costumes must be red, white, and orange. Since the order doesn't matter, let's just put this in. We know that one of the costumes is going to be this order. We also know that since
indigo and yellow are a pair, then another one of the costumes must have these two somewhere. So again, the order doesn't matter, so let's put this in somewhere else. And since no two costumes can be the same, and there's only one possible
color combination with red, that means that only one
costume can have red in it so we could even just
make a little note here saying, "These two definitely
don't have red in them." Okay, that's a lot of information, but it should put us in a great position to be able to answer the questions.