2012 CSAT, all questions

UPSC Prelims 2012 · CSAT

Question 39: Logical Reasoning and Mental Ability

Examine the following statements :

  1. 1.I watch TV only if I am bored.
  2. 2.I am never bored when I have my brother’s company.
  3. 3.Whenever I go to the theatre I take my brother along.

Which one of the following conclusions is valid in the context of the above statements ?

aIf I am bored, I watch TV.
bIf I am bored, I seek my brother’s company.
cIf I am not with my brother, then I watch TV.
dIf I am not bored, I do not watch TV.

AnswerUPSC’s answer is (d).

Statement 1 says I watch TV only if I am bored: watching TV implies being bored. Its contrapositive is that if I am not bored, I do not watch TV, which is option (d). Option (a) is the converse (bored implies TV) and does not follow. Statements 2 and 3 about the brother do not tie boredom or TV to seeking his company, so (b) and (c) also fail. Remember: 'A only if B' gives 'not B, so not A', never 'B, so A'.

Why each option is right or wrong
  • (a) Wrong. This reverses statement 1; boredom is necessary for watching TV, not sufficient.
  • (b) Wrong. Nothing says boredom makes me seek my brother's company.
  • (c) Wrong. Not being with my brother does not make me watch TV.
  • (d) Right. It is the contrapositive of statement 1: without boredom, no TV.

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

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Source: UPSC, Civil Services (Preliminary) Examination 2012, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.