Difficulty: Medium
Correct Answer: Only (3)
Explanation:
Introduction / Context:This problem asks which conclusions necessarily follow given three “some” statements across four categories. With “some,” overlaps are possible but not guaranteed unless directly stated or logically converted.
Given Data / Assumptions:
Concept / Approach:Only conclusions that must be true in every diagram consistent with the premises are valid. From “Some S are A,” we can apply conversion for “some”: “Some A are S.” Other claimed overlaps require the same individuals to be shared across different “some” statements, which is not forced.
Step-by-Step Solution:
(3) Some adhesives are seals: Directly from “Some seals are adhesives,” convert to “Some adhesives are seals.” Valid.(1) Some envelopes are seals: We have E∩G ≠ ∅ and G∩S ≠ ∅, but the overlapping members of G in each statement need not be the same element. So E∩S may be empty. Not guaranteed.(2) Some gums are adhesives: Similarly, S∩A ≠ ∅ and G∩S ≠ ∅ do not force G∩A ≠ ∅. Not guaranteed.(4) Some adhesives are gums: Again, nothing compels A to overlap with G.Verification / Alternative check:Construct a counterexample: place one item in E∩G; a different item in G∩S; and another in S∩A. All premises hold while E∩S, G∩A, and E∩A remain empty. Thus only (3) must follow.
Why Other Options Are Wrong:
Common Pitfalls:Chaining “some” statements as if they behave like “all.” Remember: “some” + “some” does not compel intersection beyond what is explicitly stated.
Final Answer:Only (3)
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