SSC CGL 2025 Tier-I · 19 September 2025, Shift 2 · General Intelligence and Reasoning · Question 17 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.

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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.

Complete the series. 60, 30, 20, 15, 12, 10, ?

(a)7.5
(b)8.57
(c)9
(d)6

Answer

Why

Correct — B.
Rule: term n = 60 ÷ n.

60 ÷ 1 = 60, 60 ÷ 2 = 30, 60 ÷ 3 = 20
60 ÷ 4 = 15, 60 ÷ 5 = 12, 60 ÷ 6 = 10

Seventh term: 60 ÷ 7 = 8.571… ≈ 8.57 → option (b).

Why the others are wrong

(a)
7.5 — 7.5 is 60 ÷ 8, the eighth term. The question mark is the seventh term, 60 ÷ 7.
(c)
9 — 9 would need a gap of exactly 1 after 10. The gaps 30, 10, 5, 3, 2 come from 60 ÷ n, and the next is 10 − 8.571 ≈ 1.43.
(d)
6 — 6 is 60 ÷ 10, the tenth term. The question mark is only the seventh place, 60 ÷ 7.

Concept

When a series falls fast and then flattens, test division by the counting numbers. Neither the differences (30, 10, 5, 3, 2) nor the ratios settle into one constant, which rules out a simple subtraction or a fixed multiplier.

The ratios give a second route. Each term is the one before multiplied by 1⁄2, 2⁄3, 3⁄4, 4⁄5, 5⁄6. The next factor is 6⁄7, and 10 × 6⁄7 = 60⁄7 ≈ 8.57.

The first six terms are whole because 60 divides exactly by 1, 2, 3, 4, 5 and 6. It does not divide by 7, so the answer is a decimal, printed rounded as 8.57 (60 ÷ 7 = 8.5714…).

Key facts

The series is 60 ÷ 1, 60 ÷ 2, … 60 ÷ 6, so the seventh term is 60 ÷ 7.
60 ÷ 7 = 8.5714…, printed to two decimals as 8.57.
60 is the LCM of 1, 2, 3, 4, 5 and 6, which is why the first six terms are whole numbers.

Study next

Series built on n², n³ and n(n + 1)Series with alternating operations (×2, +3, ×2, +3)Wrong-term items in number series

Common traps

Assuming the gaps fall to 1 and answering 9
Skipping a place and giving the eighth term, 7.5

13 Sep 2025, 12:30, Reasoning Q.8 also runs a falling series into decimals: 120, 96, 76.8, 61.44, ? multiplies by 0.8 each step (keyed d, 49.152).

Related PYQs

No directly related past PYQ was found.

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