PrepTest 156

[lcid:3723] Prep Test 156 LSAT — Logical Reasoning — S4 Logical reasoning

Question prompt

If the natural history Remaining source text redacted.
Why the credited answer is right

Credited answer: D

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

Argument or Facts

Argument

Valid or Flawed

Flawed

Strategy Overview

Argument or facts? Always argument, so identify premises and conclusions of argument Anticipate why the premises are not enough to show that the conclusion is true

Answer Anticipation

On Strengthen with a Sufficient Premise questions, we need to find the answer choice that would make the conclusion valid if added as another premise. Before figuring that out, we'll first need to identify the premises and conclusion. In this argument, the first part of the first sentence is the main conclusion. Notice how it's a two-part sentence with "for" in the middle? When a sentence is structured that way, the first part is generally a conclusion. The rest of the statements in the argument are premises as well (they're introduced with premise words like "After all" and "because"), further showing that the first part of the first sentence is the main conclusion. About half of Strengthen with a Sufficient Premise questions include "if-then" statements, so it helps to scan the premises and conclusion for "if-then" keywords. This main conclusion and one of the premises use "if," and another premise is a "trigger-outcome" statement ("renovating next year will make the museum’s expenditures exceed next year’s very tight budget"). Since there are at least three "if-then" statements, we should diagram these claims (note that we changed the order of the premises to make the argument structure easier to follow).
NOT renovate this year → Renovate next year Renovate next year → NOT stay within next year's budget

Answer choices

  1. A
    The museum will stay Remaining source text redacted.
    Why choice A is not credited

    This doesn't make the conclusion valid. Maybe the museum can stay within this year's budget and make the necessary renovations. In that case, it could stay within this year's and next year's budgets, proving the conclusion false.

  2. B
    This year's budget is Remaining source text redacted.
    Why choice B is not credited

    This doesn't make the conclusion valid. We know next year's budget is "very tight." So, (B) would make this year's budget even tighter. Still, the museum could renovate this year and stay within its budget, even if the budget's very tight. After all, we know the museum won't be able to renovate next year and stay within next year's budget, but we don't know if that's also true of this year's budget. Perhaps next year's budget includes additional expenses the museum doesn't have to worry about this year.

  3. C
    The museum will not Remaining source text redacted.
    Why choice C is not credited

    This doesn't make the conclusion valid. This answer choice runs into the same problem as (A) and (B) — it's possible that the museum could renovate this year and stay within its budget. After all, we know that if the museum doesn't renovate next year, it will have to do so this year. Although the museum won't be able to renovate next year and stay within next year's budget, we don't know if that's also true of this year. The museum's budget next year could be much tighter than this year's or include additional expenses not present this year. In that case, the museum could stay within this year's and next year's budgets, proving the conclusion false.

  4. D
    The museum will exceed Remaining source text redacted.
    Why choice D matches the stem

    This is consistent with one of our anticipated answers ("If the museum renovates this year, then it will not stay within this year's budget"), so we can confidently select (D) and move on. After all, the flipside of this answer choice is "Stay within this year's budget → NOT renovate this year." If we insert that into the original argument, the conclusion becomes valid:


    (Stay within this year's budget → NOT renovate this year)

    • NOT renovate this year → Renovate next year
    • Renovate next year → NOT stay within next year's budget

    Conclusion: Stay within this year's budget → NOT stay within next year's budget


    Therefore, this answer choice is a sufficient premise, and we can confidently select (D).

  5. E
    The museum will stay Remaining source text redacted.
    Why choice E is not credited

    This doesn't make the conclusion valid. This answer choice reverses the "if" and "then" conditions of one of our anticipated answers ("Stay within this year's budget → NOT renovate this year"). We can diagram this "if-then" statement to see that clearly: "NOT renovate this year → Stay within this year's budget."

    Inserting this answer choice into the argument wouldn't make the conclusion valid. We cannot connect this answer choice to the first premise since the shared condition ("NOT renovate this year") is the "if" condition of both statements:


    (NOT renovate this year → Stay within this year's budget)

    • NOT renovate this year → Renovate next year
    • Renovate next year → NOT stay within next year's budget

    Conclusion: Stay within this year's budget → NOT stay within next year's budget

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