SSC CGL 2024 Tier-I · 23 September 2024, Shift 2 · General Intelligence and Reasoning · Question 13 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.

The same operation(s) are followed in all the given number pairs except one. Find that odd number pair. (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)12 : 8
(b)24 : 4
(c)72 : 48
(d)36 : 24

Answer

Why

Correct — B. Test each pair as a ratio, working on the whole numbers as the note requires.

Rule: second number = first number × 2/3.

12 × 2/3 = 8, which is the pair printed
72 × 2/3 = 48, which is the pair printed
36 × 2/3 = 24, which is the pair printed
24 × 2/3 = 16, but the pair printed is 4

So 24 : 4 is the pair that does not follow the shared rule — option (b).

Why the others are wrong

(a)
12 : 8 — 12 : 8 obeys 12 × 2/3 = 8, the same two-thirds link the other regular pairs use. Following the rule is precisely what keeps it out of the answer.
(c)
72 : 48 — 72 : 48 obeys 72 × 2/3 = 48. Its numbers are the largest on offer, which makes the pair look special, but the ratio is the ordinary one.
(d)
36 : 24 — 36 : 24 obeys 36 × 2/3 = 24. Its difference of 12 is shared by neither 12 : 8 nor 72 : 48, so differences separate nothing here — the ratio does.

Concept

Odd-one-out among number pairs is decided by finding the single operation that three of the pairs share. Try the ratio before anything else.

Here 8/12, 48/72 and 24/36 all reduce to 2/3, while 4/24 reduces to 1/6. That one test finishes the question.

The note printed with the stem forbids digit-level work: you may not split 24 into 2 and 4 and operate on those. That closes off a whole family of coaching tricks and pushes you toward whole-number ratios, differences and multiples.

Differences are no help here. The three regular pairs differ by 4, 24 and 12, so the ratio is the constant, and checking it first saves a wasted subtraction pass.

Key facts

8/12, 48/72 and 24/36 all reduce to 2/3.
4/24 reduces to 1/6, which is what makes 24 : 4 the odd pair.
The note bars digit-splitting, so operations must act on 12, 24, 36, 48 and 72 as whole numbers.

Study next

Number-set items of the form (a, b, c), where operations chain across three valuesPairs linked by a square or a cube rather than by a ratioWord-pair analogies, which use the same find-the-shared-relation method on meanings

Common traps

Splitting 24 into 2 and 4 despite the note that forbids it.
Testing differences first and concluding that no rule exists.
Picking 72 : 48 because its numbers are far larger than the rest.

The same whole-numbers note heads Reasoning Q.18, Q.20 and Q.21 of this shift.

Q.18 and Q.21 ask you to match a set, Q.20 a pair, and this one wants the odd pair out. The method — name the shared operation before testing anything — is identical.

Related PYQs

No directly related past PYQ was found.