2018 CSAT, all questions
UPSC Prelims 2018 · CSAT
Question 37: Logical Reasoning and Mental Ability
If Pen < Pencil, Pencil < Book and Book > Cap, then which one of the following is always true?
aPen > Cap
bPen < Book
cPencil = Cap
dPencil > Cap
AnswerUPSC’s answer is (b).
Pen < Pencil and Pencil < Book give Pen < Book by transitivity, so that is always true. The third fact, Book > Cap, compares only Book with Cap; Cap could be anywhere below Book, so nothing is settled about how Pen or Pencil compare with Cap. In order questions, only conclusions that follow along a connected chain are certain.
Why each option is right or wrong
- (a) Pen's order against Cap is not fixed; both lie below Book.
- (b) Correct: Pen < Pencil < Book.
- (c) No fact makes Pencil equal to Cap.
- (d) Pencil's order against Cap is not fixed; both lie below Book.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2018, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.