SSC CGL 2024 Tier-I · 19 September 2024, Shift 3 · General Intelligence and Reasoning · Question 21 of 99

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 following terms will replace the question mark (?) in the given series? HDLB, LBPZ, PZTX, ? , XVBT

(a)TWXC
(b)TXXV
(c)TWWV
(d)TVWC

Answer

Why

Correct — B. Rule: each term opens with the two letters that closed the term before it, then extends that pair by +4 on the first letter and −2 on the second.

HDLB closes on LB, so term 2 opens LB. L + 4 = P and B − 2 = Z, giving LBPZ.

LBPZ closes on PZ. P + 4 = T and Z − 2 = X, giving PZTX.

PZTX closes on TX, so the missing term opens TX. T + 4 = X and X − 2 = V, giving TXXV, which is option (b).

The check: TXXV closes on XV, and the printed final term is XVBT — X + 4 wraps past Z to B, and V − 2 = T.

Why the others are wrong

(a)
TWXC — Its second letter W falls one short of the X the column D, B, Z, ?, V requires, and its last letter C abandons that same downward step entirely.
(c)
TWWV — Both middle letters read W where two different columns need X: the second column runs D, B, Z, X and the third runs L, P, T, X. W satisfies neither.
(d)
TVWC — Only the opening T survives. V, W and C each miss the second, third and fourth positions, so three of the four letters are wrong.

Concept

A four-letter cluster series can be read two ways, and here both give the same answer.

Read down the columns and each position carries its own step through the five terms: +4, −2, +4, −2.

Read across and the series overlaps — every term opens with the pair that closed the previous term, then extends it. The overlapping reading is faster because it needs only the term immediately before, and it doubles as a check on the column reading.

Either way, alphabet positions must wrap: after Z the count returns to A.

The wrap matters only in the final printed term, where X + 4 gives B. If you count without wrapping you will decide the printed series is broken and start doubting a correct rule.

Key facts

Each term opens with the two letters that closed the term before it.
Within a term, the third letter is the first plus 4 and the fourth is the second minus 2.
The four columns of the series step +4, −2, +4 and −2 respectively.
X + 4 wraps past Z to B, which is why the last term reads XVBT.

Study next

Letter-cluster series with an independent step per positionOverlapping series where each term reuses the previous term's tailAlphabet wrap-around when a step runs past Z

Common traps

Counting forward past Z without wrapping back to A
Reading the four letters as one continuous chain rather than four separate columns
Fixing only the first letter and taking the first option that begins with T

Reasoning on alphabetical positions is also set at Reasoning Q.3 and Q.7, 19 Sep 2024, 16:00 — one as an odd-one-out among letter-clusters, one as a cluster analogy. Writing the position numbers under the letters is the move that makes all three quick.

Related PYQs

No directly related past PYQ was found.