2020 CSAT, all questions

UPSC Prelims 2020 · CSAT

Question 32: Logical Reasoning and Mental Ability

Two Statements are given followed by two Conclusions : Statements : All numbers are divisible by 2. All numbers are divisible by 3.

  1. Conclusion–IAll numbers are divisible by 6.
  2. Conclusion–IIAll numbers are divisible by 4.

Which of the above Conclusions logically follows/follow from the two given Statements?

aOnly Conclusion–I
bOnly Conclusion–II
cNeither Conclusion–I nor Conclusion–II
dBoth Conclusion–I and Conclusion–II

AnswerUPSC’s answer is (a).

A number divisible by both 2 and 3 is divisible by 6, because 2 and 3 share no common factor. Conclusion I follows. Divisibility by 4 needs two factors of 2, and nothing in the statements gives a second one. For example, 6 is divisible by 2 and by 3 but not by 4. Conclusion II does not follow.

  • I. 2 and 3 have no common factor, so divisibility by both means divisibility by 6.
  • II. 6 is divisible by 2 and 3 but not by 4.
Why each option is right or wrong
  • (a) Right: only Conclusion I follows.
  • (b) Divisibility by 4 does not follow from divisibility by 2 and 3.
  • (c) Conclusion I does follow, so this is wrong.
  • (d) Conclusion II does not follow, so this is wrong.

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

Practise this paper timedPrevious questionNext question

Source: UPSC, Civil Services (Preliminary) Examination 2020, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.