Logical ReasoningDifficulty: Hard

PT13 S2 Q19 Explanation

Each year, an official estimate

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsParadox

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Stimulus

Each year, an official estimate of the stock of cod in the Grand Banks is announced. This estimate is obtained by averaging two separate estimates of how many cod are available, one based on the number of cod caught by research vessels during a once‐yearly sampling of the area and the other has been increasing markedly, by about the same amount as the sampling‐based estimate has been decreasing.

What this question is testing

Paradox

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
19.

Which one of the following, if true, most helps to account for the growing discrepancy between the estimate based on commercial tonnage

Answer choices

  1. Opposite No Timeframe Distinction7% picked this

    Fishing vessels often exceed their fishing quotas for cod and therefore often underreport the number of tons of

    We were looking for a way to explain why fishing vessels are reporting way more cod than before. This answer is going the opposite direction, talking about underreporting. Also, it doesn't present anything that is different about the last decade, compared to the previous decades.

  2. Opposite2% picked this

    More survey vessels are now involved in the yearly sampling effort than were involved

    We were looking for a way to explain why the number of cod caught by the research survey vessel was lower than before, but having more vessels out on the prowl would be a reason there would be higher counts than before.

  3. Correct64% picked this

    Improvements in technology over the last 10 years have allowed commercial fishing vessels to locate and catch large

    Why this is right

    This provides a distinction between the last decade and the previous decades. If we've made technology improvements that let fishing vessels locate and catch large schools of cod more easily, then that would explain why over the last ten years commercial vessels are catching more cod per km of net per hour. It also obliquely explains why the research vessel is finding inverse proportionally less. If the fishing vessels are getting way more efficient and grabbing cod out of the water, then when the research vessel goes to take its annual survey, it's going to count a lot fewer cod, since the fishing success has decimated the local population of cod.

    Skill tested: Paradox · how this choice captures the argument's function is the move to repeat next time.

  4. No Timeframe Distinction24% picked this

    Survey vessels count only those cod caught during a 30-day survey period, whereas commercial fishing vessels report all cod caught during

    This answer doesn't indicate that the methods have changed in the last ten years, so this is hopeless as a way to explain why the last ten years are different from the previous decades.

  5. Opposite3% picked this

    Because of past overfishing of cod, fewer fishing vessels now catch the maximum tonnage of cod each vessel is

    This answer describes a change in the past ten years, but that change points to a decreasing number of cod being caught by fishing vessels. We wanted to explain why they seem to be catching way more cod.

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