Logical ReasoningDifficulty: Easy

PT124 S1 Q9 Explanation

Global surveys estimate

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

TopicsNecessary Assumption

Keep going in LSAT Lab

  • Save & drill this skill build targeted practice sets from questions like this one

  • Video walkthroughs watch every question solved step by step

  • 81 official LSATs as questions, timed sections & full-length tests

Full official LSAT questions are available through LawHub. This page provides LSAT Lab's explanation, strategy, and review tools without republishing the full official question.

Stimulus

Global surveys estimate the earth's population of nesting female leatherback turtles has fallen by more than two-thirds in the past 15 years. Any species whose population declines by more than two-thirds in 15 years is in leatherback turtle is clearly in danger of extinction.

What this question is testing

Necessary Assumption

Your task

Find the assumption the argument requires in order for its conclusion to hold.

Common trap

Answers that would help the argument but aren't strictly required (sufficient, not necessary).

Winning move

Negate each choice — the right one breaks the argument when negated.

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

The question
9.

Which one of the following is an assumption that the

Answer choices

  1. Correct86% picked this

    The decline in the population of nesting female leatherback turtles is proportional to the decline in the leatherback

    Why this is right

    This ensures that the population of leatherback turtles as a whole has declined by two-thirds in the past 15 years.

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

  2. Out of Scope8% picked this

    If the global population of leatherback turtles falls by more than two-thirds over the next 15 years, the

    The argument is about the current state of the leatherback turtle, so this answer about the future of leatherback turtles is not relevant.

  3. Too Strong5% picked this

    The global population of leatherback turtles consists in roughly equal numbers of

    The argument does not need there to be an equal number of male and female leatherback turtles, but rather that the changes in nesting female leatherback turtles are happening across the leatherback turtle population generally.

  4. Too Strong1% picked this

    Very few leatherback turtles exist in

    There could more than just a few leatherback turtles in captivity—there could be hundreds of them in captivity—and yet the overall leatherback population could have declined by two-thirds within the past 15 years.

  5. Out of Scope0% picked this

    The only way to ensure the continued survival of leatherback turtles in the wild is to

    The argument is about the current risk of leatherback turtles going extinct. Potential solutions to the problem are not relevant unless they change the current risk level.

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free