UPSC Prelims 1996 · General Studies

Question 144: Logical Reasoning and Mental Ability

The next pair of letters in the series AZ, CX, FU, ...... is

aJQ

bKP

cIR

dIV

AnswerThe answer is (a).

First letters: A (1), C (3), F (6): the gaps are +2, +3, so the next gap is +4, giving J (10). Second letters: Z (26), X (24), U (21): the gaps are -2, -3, so the next is -4, giving Q (17). The next pair is JQ.

Why each option is right or wrong

(a) Right: J is +4 after F, and Q is -4 after U.
(b) KP is +5 and -5, not the +4 and -4 the pattern needs.
(c) IR is +3 and -3, which repeats the earlier step instead of continuing the pattern.
(d) IV moves the second letter by +1, which breaks the pattern.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 1996, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.