2016 CSAT, all questions

UPSC Prelims 2016 · CSAT

Question 32: Logical Reasoning and Mental Ability

Consider the following statements :

  1. 1.Either A and B are of the same age or A is older than B
  2. 2.Either C and D are of the same age or D is older than C
  3. 3.B is older than C

Which of the following conclusions can be drawn from the above statements ?

aA is older than B
bB and D are of the same age
cD is older than C
dA is older than C

AnswerUPSC’s answer is (d).

Write the premises as ages: A >= B, D >= C and B > C. Chain the first and third: A >= B > C, so A is strictly older than C (option d). A > B is not forced because equal ages are allowed, B = D is not stated, and D > C is not forced because D may equal C. Remember: one strict link in a chain makes the end-to-end comparison strict.

Why each option is right or wrong
  • (a) Equal ages are allowed, so A > B is not forced.
  • (b) Nothing links the ages of B and D.
  • (c) D may be the same age as C.
  • (d) Right: A >= B and B > C give A > C.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2016, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.