SSC CGL 2024 Tier-I · 25 September 2024, Shift 1 · 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 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. (24, 15, 120) (21, 19, 133) (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/deleting/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)(31, 9, 96)
(b)(18, 16, 99)
(c)(27, 12, 108)
(d)(33, 10, 170)

Answer

Why

Correct — C. Test the two given sets for one operation that uses both of the first two numbers whole.

Rule: first × second ÷ 3 = third.

24 × 15 = 360, and 360 ÷ 3 = 120 ✓
21 × 19 = 399, and 399 ÷ 3 = 133 ✓

Carry it to the options: 27 × 12 = 324, and 324 ÷ 3 = 108, which is option (c).

Why the others are wrong

(a)
(31, 9, 96) — (31, 9, 96): 31 × 9 = 279 and 279 ÷ 3 = 93, not 96. It misses by three, which is close enough to survive a glance rather than a calculation.
(b)
(18, 16, 99) — (18, 16, 99): 18 × 16 = 288 and 288 ÷ 3 = 96, not 99.
(d)
(33, 10, 170) — (33, 10, 170): 33 × 10 = 330 and 330 ÷ 3 = 110, nowhere near 170.

Concept

The bracketed NOTE on this item is doing real work. It forbids splitting a number into digits, so any rule must treat 24 as twenty-four and never as a 2 and a 4.

That closes off most of the search space. What is left is arithmetic on whole numbers: a sum, a difference, a product, or a product scaled by a small constant.

Here the product of the first two numbers is three times the third, and the same constant works on both given sets. That is what makes it the rule rather than a coincidence.

A single set can be matched by accident. Always confirm a candidate rule on the second given set before carrying it to the options — that second check is the whole reason SSC supplies two sets.

Key facts

24 × 15 = 360 and 360 ÷ 3 = 120, so the rule holds on the first given set.
21 × 19 = 399 and 399 ÷ 3 = 133, so it holds on the second given set as well.
The NOTE forbids digit-splitting, so every operation must use each number whole.

Study next

Number-set analogies whose rule is a difference plus a fixed constantRules of the form a × b − c on three-number setsJudging from the size of the third number whether the rule is additive or multiplicative

Common traps

Verifying the rule on the first set only and then taking the option that nearly fits — (31, 9, 96) misses by three.
Breaking a two-digit number into its digits, which the question's NOTE explicitly rules out.

SSC prints this item with the digit-splitting NOTE attached and asks you to carry a rule verified on two sample sets across to a fourth. It is also asked at 10 Sep 2024, 09:00, Reasoning Q.9, where the rule is a − b = 21 with c = b + 4, and at 10 Sep 2024, 16:00, Reasoning Q.5, where it is b = 2a − 100.

Related PYQs

No directly related past PYQ was found.