2023 CSAT, all questions

UPSC Prelims 2023 · CSAT

Question 75: Logical Reasoning and Mental Ability

Consider the sequence ABC_ _ ABC_ DABBCD_ ABCD that follows a certain pattern. Which one of the following completes the sequence ?

aDACB
bCDAB
cDCCA
dDDCA

AnswerUPSC’s answer is (d).

Fill the four blanks in order. With option (d), DDCA, the string becomes ABCD DABC CDAB BCDA ABCD. Each block of four is the previous block with its last letter moved to the front: ABCD, DABC, CDAB, BCDA, ABCD. The pattern then repeats, so DDCA completes the sequence.

Why each option is right or wrong
  • (a) Wrong: it makes the second block AABC, which breaks the pattern.
  • (b) Wrong: it makes the first block ABCC, which breaks the pattern.
  • (c) Wrong: it makes the second block CABC, which breaks the pattern.
  • (d) Right: the blocks ABCD, DABC, CDAB, BCDA, ABCD each shift by one place.

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

Practise this paper timedPrevious questionNext question

Source: UPSC, Civil Services (Preliminary) Examination 2023, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.