SSC CGL 2025 Tier-I · 19 September 2025, Shift 3 · General Intelligence and Reasoning · Question 25 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

The series given below contains a sequence of numbers. Accordingly identify the incorrect combination. 5, 8, 16, 19, 39, 41, 81

(a)16, 39
(b)16, 41
(c)39, 81
(d)41, 81

Answer

Why

Correct — C.
Rule: alternate + 3 and × 2.

5 + 3 = 8 ✓
8 × 2 = 16 ✓
16 + 3 = 19 ✓
19 × 2 = 38, not 39 ✗

38 + 3 = 41 ✓
41 × 2 = 82, not 81 ✗

The wrong pair is 39, 81 → option (c).

Why the others are wrong

(a)
16, 39 — 16 is 8 × 2, on the rule. This pair catches 39 but misses 81, which should be 41 × 2 = 82.
(b)
16, 41 — 16 and 41 both fit: 16 = 8 × 2 and 41 = 38 + 3. Neither printed error, 39 or 81, is in this pair.
(d)
41, 81 — 41 is right: it is 38 + 3. It only looks wrong beside the printed 39, since 39 + 3 = 42.

Concept

In a wrong-term item, find the rule from the terms that agree, then test each term against it. Here the steps alternate, + 3 then × 2, giving 5, 8, 16, 19, 38, 41, 82.

Test each term against the corrected value before it. 41 fails against the printed 39 (39 + 3 = 42) but fits the rule's 38, so 39 and 81 are the wrong terms.

The pair format means both wrong terms must be found. Stopping at 39 still leaves (a) and (c) in play.

Key facts

Corrected series: 5, 8, 16, 19, 38, 41, 82.
+ 3 on the 1st, 3rd and 5th steps, × 2 on the 2nd, 4th and 6th.
A wrong term can make its neighbour look wrong, so compare against the rule, not the printed neighbour.

Study next

Wrong-term series with a single wrong numberSeries alternating addition and multiplicationTwo interleaved series in one line

Common traps

Marking 41 wrong because 39 + 3 = 42, when the check must use 38
Stopping at the first wrong term and choosing a pair that holds only 39

19 Sep 2025, 09:00, Reasoning Q.25 asks for the same 'incorrect combination' pair: 3, 12, 48, 194, 768, 3074 on a × 4 rule, keyed 194, 3074 (d).

Related PYQs

No directly related past PYQ was found.