PrepTest 157

[lcid:3726] Prep Test 157 LSAT — Logical Reasoning — S3 Logical reasoning

Question prompt

A smaller number of Remaining source text redacted.
Why the credited answer is right

Credited answer: B

The notes below walk through why it fits the stem and how to eliminate the rest.

Argument or Facts

Argument

Valid or Flawed

Valid

Strategy Overview

Argument or facts? Always argument, so identify premises and conclusions of argument Diagrammable?
If yes, diagram out premises and conclusion. Note key identifiable characteristics of argument (How many premises? Quantifiers? Ands/ors? Contrapositives? Transitives?) Can also convert specific terms in diagram to As, Bs, Cs, Ds, etc.
Eliminate an answer choice as soon as you notice it doesn't possess a key identifiable characteristic the passage possesses Diagram remaining until you find a matching diagram
If not, paraphrase the method of reasoning
Keep in mind common methods of reasoning, like argument by analogy Select answer choice that uses the same method of reasoning

Answer Anticipation

Parallel Reasoning questions task us with finding the answer choice with the same argumentative structure as the argument in the passage. There are two ways we can look beyond the subject matter of the passage to uncover its underlying structure. One route is to diagram the premises and conclusions (if at least some of them are "if-then," "most," or "some" statements). Alternatively, we can describe the argumentative strategy (if the premises and conclusion are not conditional and do not involve quantifiers). None of the statements in this argument is an "if-then," "most," or "some" statement, so we are better off attempting to describe the argumentative structure. Some test-takers like to use the "Kirkland" strategy to describe an argument's structure rather than its content. To use the "Kirkland" strategy, we'll simply remove any reference to the subject matter and replace it with a generic descriptor (much like Costco replaces brand-named items with generic "Kirkland" versions of those products). So, let's replace "short documentary films" and "full-length science-fiction films" with the generic "As" and "Bs." (There's a slight difference between the two premises — distinguishing from "full-length science-fiction films" and just "science-fiction films." This distinction doesn't affect the argument's validity — if there are fewer science-fiction films in general, there are definitely fewer full-length science-fiction films — so we'll ignore this difference in our Kirkland version.) We'll also replace "commercially successful" with "C." The phrases "smaller number" and "a higher percentage" are generic already, so we can leave them in. The Kirkland version of this argument is, "Fewer As than Bs are C. But there are more As than Bs. So, a higher percentage of Bs than As are C." (You could make this even more formulaic if you'd like: "The number of Bs that are Cs > the number of As that are Cs. The number of As is bigger than the number of Bs. So the percentage of Bs that are Cs > the percentage of As that are Cs.") Now, let's see which answer choice matches this generic description of the argument. We can also expedite our review of the answer choices if we take a conclusion-out approach. We should compare each conclusion to the Kirkland version of our conclusion — that "a higher percentage of Bs than As are C." If an answer choice's conclusion doesn't resemble that, we can eliminate it without bothering with the answer choice's premises.

Answer choices

  1. A
    A greater number of Remaining source text redacted.
    Why choice A is not credited

    This conclusion resembles the claim that "a higher percentage of Bs than As are C" (it says "smaller percentage," but that's close enough for this stage of analysis). So, let's take a closer look at this one to see if it matches the full Kirkland version of the passage ("Fewer As than Bs are C. But there are more As than Bs. So, a higher percentage of Bs than As are C.")

    Checking out the premises, we can't find any equivalent to "But there are more As than Bs." That's enough reason to cross off (A). Without that premise, this argument is flawed, unlike the passage. Even if there is a smaller number of large Victorian apartments with freestanding bathtubs, there may still be a larger percentage of large Victorian apartments with freestanding bathtubs—especially if there are far fewer large Victorian apartments than small modern apartments.

  2. B
    A greater number of Remaining source text redacted.
    Why choice B matches the stem

    This one matches the generic version of our argument!

    This conclusion resembles the claim that "a higher percentage of Bs than As are C." So, we'll take a closer look at this one to see if it matches the full Kirkland version of the passage ("Fewer As than Bs are C. But there are more As than Bs. So, a higher percentage of Bs than As are C.")

    We'll have to be careful with how we assign our A and B to this answer choice. The first premise says that a "greater number of large Victorian apartments than of modern apartments have freestanding bathtubs." To line up with "Fewer As than Bs are C," we'll have to make "small modern apartments" our "A" variable (the smaller variable), "large Victorian apartments" our "B" (the bigger variable), and "freestanding bathtubs" our "C." So, with some re-arranging, the first premise sounds like "Fewer As than Bs are C."

    The second premise establishes that there are more As (modern apartments) than Bs (Victorian apartments), which aligns with "But there are more As than Bs."

    And, as discussed, the conclusion establishes that a higher percentage of Bs (large Victorian apartments) than As (modern apartments) have Cs (freestanding bathtubs). This matches the Kirkland conclusion that "a higher percentage of Bs than As are C."

    Like the passage, this is a valid argument. If there are more large Victorian apartments with freestanding bathtubs despite the fact that there are fewer Victorian apartments overall, there would need to be a greater percentage of Victorian apartments with freestanding bathtubs. By analogy, if you and I were both eating a pie, and I ate more pie than you even though my pie was much smaller than yours, I would have had consumed a greater percentage of my pie. The same reasoning applies to films and apartments for this question.

  3. C
    A smaller number of Remaining source text redacted.
    Why choice C is not credited

    If you misread the last clause as the main conclusion, this argument is identical to the passage (and to answer choice (B)). However, the last clause is not this passage's main conclusion. The first sentence is the main conclusion.

    Notice how the first sentence is followed by another sentence that begins with "For"? The structural word "for" almost always comes after a conclusion. Moreover, the word "for" always introduces a premise. And while the claim "even though there are more small modern apartments than there are Victorian apartments" comes immediately after the word "for," that claim is just a concession. The word "for" really introduces the claim that "a higher proportion of large Victorian apartments than of small modern apartments have freestanding bathtubs." So, the main conclusion is not that last claim, but the first one: "A smaller number of small modern apartments than of large Victorian apartments have freestanding bathtubs."

    Since the main conclusion is about numbers ("smaller number"), it does not resemble our Kirkland conclusion that "a higher percentage of Bs than As are C." For this reason, we can cross off (C).

  4. D
    A greater number of Remaining source text redacted.
    Why choice D is not credited

    This conclusion appears halfway through the argument. The conclusion is introduced by the conclusion word "so" and is the first half of a two-part sentence with "since" in the middle. These structural clues tell us that "there are more small modern apartments than there are large Victorian apartments" is the argument's main conclusion.

    Since the main conclusion is about numbers ("more"), it does not resemble our Kirkland conclusion that "a higher percentage of Bs than As are C." For this reason, we can cross off (D).

  5. E
    A smaller number of Remaining source text redacted.
    Why choice E is not credited

    This conclusion resembles the claim that "a higher percentage of Bs than As are C." So, let's take a closer look at this one to see if it matches the full Kirkland version of the passage ("Fewer As than Bs are C. But there are more As than Bs. So, a higher percentage of Bs than As are C.")

    We'll have to be careful with how we assign our A and B to this answer choice. The first premise says that a "smaller number of modern apartments than of Victorian apartments have freestanding bathtubs." To line up with "Fewer As than Bs are C," we'll have to make "modern apartments" our "A" variable (the smaller variable), "Victorian apartments" our "B" (the bigger variable), and "freestanding bathtubs" our "C." With that framing, the first premise sounds like "Fewer As than Bs are C."

    The second premise says "even though there are fewer modern apartments than there are large Victorian apartments." This means the second premise establishes that there are fewer As than Bs. This doesn't line up with the second premise that "there are more As than Bs." That's enough to eliminate (E).

    We can eliminate (E) because, unlike the passage, it is a flawed argument. Even if there are fewer modern apartments with freestanding bathtubs, there could still be a higher percentage of modern apartments with freestanding bathtubs — especially if there are significantly fewer modern apartments than Victorian apartments. (Suppose only 1 modern apartment has a freestanding bathtub, but there are only 2 modern apartments overall. If there are 5 Victorian apartments with freestanding tubs but 100 Victorian apartments overall, 50% of modern apartments would have freestanding tubs, but only 5% OF Victorian apartments would have freestanding tubs.)

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