UPSC Prelims 2022 · CSAT
Question 38: Logical Reasoning and Mental Ability
Two Statements followed by four Conclusions are given below. You have to take the Statements to be true even if they seem to be at variance from the commonly known facts. Read all the Conclusions and then decide which of the given Conclusions logically follows/follow from the Statements, disregarding the commonly known facts :
- Statement–1All pens are books.
- Statement–2No chair is a pen.
- Conclusion–IAll chairs are books.
- Conclusion–IISome chairs are pens.
- Conclusion–IIIAll books are chairs.
- Conclusion–IVNo chair is a book.
Which one of the following is correct?
AnswerUPSC’s answer is (d).
Draw circles: pens lie wholly inside books, and no chair overlaps pens. Chairs may or may not overlap the rest of books. I (all chairs are books) need not hold. II (some chairs are pens) contradicts statement 2. III (all books are chairs) need not hold: books outside pens may or may not be chairs. IV (no chair is a book) need not hold, since chairs may overlap books outside pens. None follows.
- I. Chairs may lie wholly outside books.
- II. Contradicts the statement that no chair is a pen.
- III. Books outside pens may or may not be chairs.
- IV. Chairs may overlap books outside pens.
Why each option is right or wrong
- (a) Wrong: chairs could lie wholly outside books.
- (b) Wrong: it contradicts statement 2 (no chair is a pen).
- (c) Wrong: neither III nor IV is forced by the statements.
- (d) Correct: each conclusion may hold or fail.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2022, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.