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Difficulty: EasyMust Be True / Most Strongly Supported

Every manuscript in the municipal archive that was created before 1750 is stored in a climate-controlled vault. Any archive document stored in a climate-controlled vault requires written authorization from the head archivist to be accessed. Today, researcher Evelyn was granted access to a municipal archive document without written authorization from the head archivist.

Based on the statements above, which of the following statements must be true? (Select all that apply.)

  1. The document accessed by Evelyn is not stored in a climate-controlled vault.Answer
  2. B
    Any municipal archive document created after 1750 does not require written authorization to be accessed.
  3. The document accessed by Evelyn was not created before 1750.Answer
  4. D
    Every document in the municipal archive that is not stored in a climate-controlled vault was accessed by researchers today.
  5. E
    Obtaining written authorization from the head archivist guarantees that a researcher will be granted access to any pre-1750 document.

Answer

The statements establishing that the document accessed by Evelyn is not stored in a climate-controlled vault and that the document was not created before 1750 must both be true.
The stimulus establishes a transitive conditional chain: if a manuscript was created before 1750, it is kept in the vault; if it is in the vault, written authorization is required to access it. Modus tollens (contrapositive reasoning) dictates that if a document is accessed without written authorization, it cannot be in the vault, and consequently, it cannot have been created before 1750.

Step-by-Step Solution

1
Symbolize the conditional rules in the stimulus
Created before 1750 implies Stored in vault; Stored in vault implies Requires written authorization. Chained: Created before 1750 implies Requires written authorization.
Establishing the conditional relationships enables valid deductive inferences via modus tollens.
2
Apply the given factual premise to the conditional chain
Evelyn accessed a document with No written authorization, triggering the contrapositives: Not stored in vault, and Not created before 1750.
The negation of a necessary condition guarantees the negation of the sufficient condition.
3
Evaluate the choices against the deduced contrapositives
Identify the choices reflecting that the document is not in a vault and not created before 1750 as logically certain, while rejecting mistaken reversals, necessary-sufficient confusions, and unjustified universal claims.
Must Be True questions require strictly valid deductions with no unsupported assumptions.

Key Concept

Conditional logic chains and contrapositive deduction
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Must Be True / Most Strongly Supported

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