SSC CGL 2025 Tier-I · 23 September 2025, Shift 3 · General Intelligence and Reasoning · Question 15 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 13 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.

What should come at the place of question mark? : 101, 94, 87, 80, 73, ?

(a)66
(b)65
(c)64
(d)67

Answer

Why

Correct — A.
Rule: subtract 7 each time.

101 − 7 = 94
94 − 7 = 87
87 − 7 = 80
80 − 7 = 73

Next: 73 − 7 = 66 → option (a).

Why the others are wrong

(b)
65 — 65 is 73 − 8. Every gap in the series is exactly 7, so one more step of 7 from 73 gives 66, not 65.
(c)
64 — 64 is 73 − 9, a gap of 9. The series never changes its step of 7, so this overshoots by 2.
(d)
67 — 67 is 73 − 6, a gap of 6 — one short of the constant 7 that every earlier step uses.

Concept

This is an arithmetic progression running downwards: every term is 7 less than the one before. Check the gap at every step, not just the first, before trusting it.

A remainder check confirms the answer without extending the series. Every term is a multiple of 7 plus 3: 101 = 98 + 3 and 73 = 70 + 3.

Of the options, 66 = 63 + 3 keeps that remainder, while 65, 64 and 67 leave 2, 1 and 4.

Key facts

In an arithmetic progression the difference between consecutive terms is constant, here −7.
nth term = first term + (n − 1) × difference: 101 + 5 × (−7) = 66 for the sixth term.
Every term of this series leaves remainder 3 when divided by 7.

Study next

Series whose differences themselves change, such as −3, −6, −9Series of squares or cubes counted downwardsFinding the wrong term in an arithmetic series

Common traps

Checking only the first gap and assuming the rest, which fails on series whose step changes.

22 Sep 2025, 09:00, Reasoning Q.21 also counts down from 100, but its gaps grow — −3, −6, −9, −12 — and it is keyed 70.

20 Sep 2025, 12:30, Reasoning Q.23 descends through perfect squares (100, 81, 64, 49), keyed 36.

Related PYQs

No directly related past PYQ was found.

Topic: Number Series — all 178 SSC CGL questions on it, every solved shift.