SSC CGL 2024 Tier-I · 19 September 2024, Shift 2 · General Intelligence and Reasoning · Question 19 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.

Select the option that represents the letters that when sequentially placed from left to right in the blanks below will complete the letter series. _ B _ _ _ A L _ _ L _ _

(a)BLABBALL
(b)BBALLBAA
(c)LBAALLBA
(d)LALBBABA

Answer

Why

Correct — D. Rule: the block LBA repeats across all twelve places.

The printed letters are B at place 2, A at place 6, and L at places 7 and 10.
Two L's three places apart fix the block length at 3, so places 1, 4, 7 and 10 all carry L.
B at place 2 and A at place 6 then fix the block as L B A.

The full line reads L B A L B A L B A L B A.

Reading off the eight blanks in order gives L, A, L, B, B, A, B, A — option (d).

Why the others are wrong

(a)
BLABBALL — BLABBALL puts B at place 1, so the line would open B B, and no three-letter block can repeat from there.
(b)
BBALLBAA — BBALLBAA puts B at place 1 and B at place 3, giving an opening of B B B against a printed B at place 2.
(c)
LBAALLBA — LBAALLBA opens correctly with L, but its next letter puts B at place 3, so the line reads L B B where it needs L B A.

Concept

Blank-filling letter series are solved from the printed letters, not by testing the options. Number the places first and mark what is given.

The strongest clue in this line is the pair of L's at places 7 and 10 — three apart. A repeated letter three places apart points to a block of length 3.

With a block of 3, places 1, 4, 7 and 10 share a letter, places 2, 5, 8 and 11 share one, and places 3, 6, 9 and 12 share one. The printed B at 2 and A at 6 finish the job.

Only two options begin with L, which the block length already demands, so half the field goes before any letter-by-letter checking.

Key facts

Two identical letters three places apart point to a repeating block of length three.
In a block of length 3, places 1, 4, 7 and 10 all carry the same letter.
The completed line here is L B A L B A L B A L B A.

Study next

Repeating-block letter series and how to read the block length off repeated lettersSeries in which two different blocks alternateAlphabet-position series where letters shift by a constant, as at Reasoning Q.21 of this shift

Common traps

Testing all four options letter by letter instead of deriving the block from what is printed.
Losing count of the blanks, which here are places 1, 3, 4, 5, 8, 9, 11 and 12.
Mis-copying the underscores, so twelve places become eleven or thirteen.

The line is printed with underscores and the option supplies the blanks left to right, so a numbered grid is worth the seconds it costs. Reasoning Q.10 of this shift runs a letter-cluster series that rewards the same discipline.

Related PYQs

No directly related past PYQ was found.