SSC CGL 2024 Tier-I · 9 September 2024, Shift 3 · General Intelligence and Reasoning · Question 15 of 100

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 6 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

Which of the four options will replace the question mark (?) in the following series? XF 11 , YI 15, ZL 19 , AO 23, ?

(a)BR 27
(b)CQ 25
(c)CR 25
(d)BP 26

Answer

Why

Correct — A. Three separate tracks run side by side and never interact.

Rule: first letter +1, second letter +3, number +4.

First letters: X, Y, Z, A, B (the alphabet wraps past Z back to A).
Second letters: F, I, L, O, R.
Numbers: 11, 15, 19, 23, 27.

Putting the three tracks back together gives BR 27, option (a).

Why the others are wrong

(b)
CQ 25 — Its first letter is C. The first letters step by one — X, Y, Z, A — so the fifth term must start at B, and C is one place too far.
(c)
CR 25 — Its number is 25, a step of only +2. The number track moves in fixed jumps of +4 from 11, 15, 19, 23, which lands on 27.
(d)
BP 26 — Its second letter is P. The second letters climb by three each time from F, I, L, O, so O has to become R.

Concept

An alphanumeric series carries two or three independent sequences in one term. Treat each position as its own column and the item collapses into three easy checks.

The number track is the fastest way in. A constant +4 settles the last part of the answer before you touch the alphabet at all.

The letters are where the difficulty sits, because a +1 step and a +3 step are easy to swap under time pressure.

The wrap from Z to A between the third and fourth terms is the only point where the series stops looking arithmetic, and it is where most wrong answers start.

Key facts

The first letters run X, Y, Z, A, B — a plain +1 with a wrap past Z.
The second letters run F, I, L, O, R — a plain +3.
The numbers run 11, 15, 19, 23, 27 — a constant +4.

Study next

Alphanumeric series whose number track is a squares or primes runLetter series that wrap the alphabet forwards and backwards

Common traps

Giving the first letter the +3 step and the second letter the +1 step.
Stopping the first-letter track at Z instead of wrapping round to A.

The same paper runs a pure letter-cluster version at 09 Sep 2024, 16:00, Reasoning Q.2 (MFT, NIS, PLQ, SON, WRJ, ?), where each of three letters moves on its own step and no number track helps you.

Related PYQs

No directly related past PYQ was found.