SSC CGL 2024 Tier-I · 13 September 2024, Shift 1 · General Intelligence and Reasoning · Question 21 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 10 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 set in which the numbers are related in the same way as are the numbers of the following set. 7 — 14 — 23 4 — 11 — 20 NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 – Operations on 13 such as adding/subtracting/multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)

(a)7 — 15 — 22
(b)5 — 12 — 21
(c)9 — 12 — 22
(d)15 — 30 — 20

Answer

Why

Correct — B. Take the two gaps inside each given triple and check they are the same two gaps.

7 → 14 → 23 gives +7, then +9
4 → 11 → 20 gives +7, then +9

Rule: +7 then +9.

Option (b): 5 + 7 = 12, and 12 + 9 = 21. Both printed numbers match the signature, so it is the set built the same way → option (b).

Why the others are wrong

(a)
7 — 15 — 22 — Option (a) runs 7 → 15 → 22, gaps of +8 then +7. The first step is already one too large, so it fails before the second gap matters.
(c)
9 — 12 — 22 — Option (c) runs 9 → 12 → 22, gaps of +3 then +10. Neither step matches the signature, and its total spread of 13 falls short of the 16 both given triples cover.
(d)
15 — 30 — 20 — Option (d) runs 15 → 30 → 20, and its second gap is −10. Both given triples rise throughout, so a falling step disqualifies it outright.

Concept

An in-set relation asks what links the numbers within one set, not what links one set to another. With three numbers, compute both consecutive differences and treat the pair as a signature.

Here the signature is (+7, +9) and it repeats in the second triple, which is what turns it from a coincidence into a rule. Always confirm on the second example before using it.

Then test each option in one pass. As soon as a gap disagrees you can stop — there is no need to compute the second gap of a set whose first gap is already wrong.

The gaps are unequal, so this is not an arithmetic progression, and any method that assumes a single common difference will reject the correct set.

Key facts

Both given triples step +7 and then +9.
5, 12, 21 reproduces that signature exactly.
The total spread of each triple is 16, since 7 + 9 = 16.

Study next

In-set relations with a constant difference across all three numbersSet analogies where the relation is multiplicative rather than additive

Common traps

Assuming a constant difference and hunting for an arithmetic progression.
Looking for a relation across the two given triples instead of inside each one.
Reading the em dashes in 7 — 14 — 23 as minus signs.

The same in-set-gap idea with a constant step is at 11 Sep 2024, 16:00, Reasoning Q.9 on (66, 57, 48) and (94, 85, 76), where every gap is −9.

A multiplicative version, (3, 9, 27) and (4, 16, 64), is set at 23 Sep 2024, 12:30, Reasoning Q.18 — same instruction, a different family of relation.

Related PYQs

No directly related past PYQ was found.