Difficulty: Medium
Correct Answer: None follows
Explanation:
Introduction / Context:
This item is designed to expose two common errors: (1) inferring converses (e.g., from A ⊆ B to B ⊆ A), and (2) forcing intersections without evidence. We must test each conclusion strictly against the premises.
Given Data / Assumptions:
Concept / Approach:
Conclusions that reverse an inclusion (e.g., “All glasses are plastics”) are invalid. Claims that everything in a larger set must be inside a smaller subset (“All liquids are sponges”) also fail absent explicit premises. Finally, while Clothes ⊆ Liquids is true, the converse “All liquids are clothes” is not supported.
Step-by-Step Solution:
Verification / Alternative check:
Model: Let Plastics be a tiny subset of Glasses, Sponges a separate subset of Glasses, Clothes a large set contained in Liquids, and Liquids much larger. All premises hold; none of I–IV must be true.
Why Other Options Are Wrong:
Options claiming II and/or IV rely on unjustified overlaps or converses.
Common Pitfalls:
Converse errors and assuming that if a subset lies inside a superset, then the superset collapses back into the subset.
Final Answer:
None follows.
Discussion & Comments