Logical ReasoningDifficulty: Easy

PT130 S1 Q20 Explanation

A person with a type B

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

TopicsMust be True

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Stimulus

A person with a type B lipid profile is at much greater risk of heart disease than a person with a type A lipid profile. In an experiment, both type A volunteers and type B volunteers were put on a low­ fat diet. The cholesterol levels of the type B volunteers soon the diet, and 40 percent of them actually shifted to type B profiles.

What this question is testing

Must be True

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.

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The question
20.

If the information above is true, which one of the following must

Answer choices

  1. Unsupported3% picked this

    In the experiment, most of the volunteers had their risk of heart disease reduced at least marginally as a result of having

    While it must be true that some of the volunteers had their risk of heart disease increase, those who originally had type B profiles remained with type B profiles and for them no change in their risk of heart disease can be inferred. For the those who originally had type A profiles, 40 percent of them had their risk of heart disease increase since their profiles switched to type B. For the remainder of type A profiles, no change can be inferred.

  2. Supports a Premise8% picked this

    People with type B lipid profiles have higher cholesterol levels, on average, than do people with

    This could explain why people with type B profiles have a higher risk of heart disease, though this does not have to be true.

  3. Out of Scope5% picked this

    Apart from adopting the low-fat diet, most of the volunteers did not substantially change any aspect of their lifestyle that would have affected

    Other changes to lifestyle are not discussed in the statements.

  4. Too Strong3% picked this

    The reduction in cholesterol levels in the volunteers is solely responsible for the change in

    This could be true, but there could be factors other than the reduction of cholesterol levels that contributed to their lipid profile changing.

  5. Correct81% picked this

    For at least some of the volunteers in the experiment, the risk of heart disease increased after having been

    Why this is right

    Since 40 percent of the type A volunteers shifted to type B profiles and a person with a type B lipid profile is at much greater risk of heart disease than a person with a type A lipid profile, it follows that for some volunteers the risk of heart disease increased after having been put on the low-fat diet.

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

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