SSC CGL 2024 Tier-I · 12 September 2024, Shift 2 · General Intelligence and Reasoning · Question 2 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 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.

Two sets of numbers are given below. In each set of numbers, certain mathematical operation(s) on the first number result(s) in the second number. Similarly, certain mathematical operation(s) on the second number result(s) in the third number and so on. Which of the given options follows the same set of operations as in the given sets? (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into their constituent digits. E.g. 13 – Operations on 13 such as adding/subtracting/multiplying to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.) 10 – 12 – 8 – 15; 12 – 14 – 10 – 19

(a)8 – 6 – 10 – 18
(b)11 – 13 – 9 – 17
(c)6 – 8 – 12 – 16
(d)15 – 13 – 9 – 19

Answer

Why

Correct — B. Rule: +2, then −4, then double and subtract 1.

10 → 12 (+2) → 8 (−4) → 8 × 2 − 1 = 15
12 → 14 (+2) → 10 (−4) → 10 × 2 − 1 = 19

Run option (b) through the same three links:
11 → 13 (+2) → 9 (−4) → 9 × 2 − 1 = 17, which is the fourth number printed.

Why the others are wrong

(a)
8 – 6 – 10 – 18 — The chain fails at the very first link: 8 + 2 = 10, not 6. Nothing later can repair that.
(c)
6 – 8 – 12 – 16 — The first link holds (6 + 2 = 8), but the second breaks — 8 − 4 = 4, not 12.
(d)
15 – 13 – 9 – 19 — 15 + 2 = 17, not 13. The second number falls where both sample sets rise.

Concept

These two-sample operator questions hand you two worked chains and ask which option obeys the same one. Fix the operation at each link from the samples, then test an option link by link and stop at its first failure.

The rider attached to the question matters: operate on whole numbers, so 13 stays 13 and is never split into 1 and 3.

The third link here is not a plain addition. 8 → 15 and 10 → 19 are both double, then subtract 1, and reading the first as +7 makes the second sample look broken.

The third link can equally be written as fourth = second + third − 5, which reproduces 15, 19 and 17. Any equivalent form is fine as long as it fits both sample sets, not just one.

Key facts

Both sample chains share their first two links, +2 and then −4.
The third link doubles and subtracts 1: 8 gives 15, 10 gives 19, 9 gives 17.
The printed rider bars digit-splitting, so every operation acts on the whole number.

Study next

Operator chains whose links multiply or square rather than addSingle-pair number analogies such as 346 : 245Testing each option against a fixed rule instead of inferring a rule from an option

Common traps

Reading the third link as +7 from the first sample, which then fails on the second
Breaking a two-digit number into digits, which the question explicitly forbids
Checking only an option's last number instead of every link in its chain

The same two-sample format is asked at 12 Sep 2024, 09:00, Reasoning Q.5 and at 25 Sep 2024, 12:30, Reasoning Q.9, both carrying the identical whole-numbers rider. A single-pair version, 346 : 245 and 580 : 479, is asked at 12 Sep 2024, 12:30, Reasoning Q.18.

Related PYQs

No directly related past PYQ was found.

Two sets of numbers are given below. In each set of numbers, certain mathematical operation(s) on the first number result(s) in the second number. Similarly, certain mathematical operation(s) on the second number result(s) in the third number and so on. Which of the given options follows the same set of operations as in the given sets? (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into their constituent digits. E.g. 13 – Operations on 13 such as adding/subtracting/multiplying to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.) 10 – 12 – 8 – 15; 12 – 14 – 10 – 19

(a)8 – 6 – 10 – 18
(b)11 – 13 – 9 – 17
(c)6 – 8 – 12 – 16
(d)15 – 13 – 9 – 19