Directions: In the question given below there are some statements followed by…

2025

Directions: In the question given below there are some statements followed by some conclusions. You have to take the given statements to be true even if they seem to be at variance with commonly known facts. Read all the conclusions and then decide which of the given conclusions logically follows from the given statements disregarding commonly known facts.

Statements:

All machines are instruments.

All instruments are humans.

Conclusions:

I. All humans are instruments.

II. All machines are humans.

  1. A.

    Only I follows

  2. B.

    Only II follows

  3. C.

    Both I and II follow

  4. D.

    Either I or II follows

Show answer & explanation

Correct answer: B

Concept:

"All A are B" means every member of A lies inside B (A is a subset of B). This containment does not automatically reverse — A being inside B does not make B lie inside A, unless the two sets are known to be equal. Containment is, however, transitive: if A is inside B and B is inside C, then A is definitely inside C in every arrangement consistent with the statements.

Application:

  1. "All machines are instruments" places Machines inside Instruments.

  2. "All instruments are humans" places Instruments inside Humans.

  3. By transitivity, Machines is inside Instruments which is inside Humans, so Machines lies inside Humans in every valid arrangement — Conclusion II ("All machines are humans") holds definitely.

  4. Conclusion I ("All humans are instruments") would need Humans to lie inside Instruments — the reverse of the second statement. Only Instruments-inside-Humans is given, never the reverse, so Conclusion I is not guaranteed.

Cross-check:

Draw the most general diagram consistent with both statements: three concentric circles, Humans as the outermost, Instruments a smaller circle fully inside Humans, and Machines the smallest circle fully inside Instruments.

  • Instruments is a proper (smaller) part of Humans in this diagram, so Humans is not fully inside Instruments — Conclusion I fails here.

  • Machines stays fully inside Humans in this diagram, and in every other diagram consistent with the two statements — Conclusion II always holds.

Hence, only Conclusion II follows.

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