SSC CGL 2024 Tier-I · 17 September 2024, Shift 2 · General Intelligence and Reasoning · Question 19 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.

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)40 : 52
(b)45 : 54
(c)35 : 42
(d)55 : 66

Answer

Why

Correct — A. Read each pair as a ratio rather than as a difference.

Rule: second = first × 6⁄5, that is, every pair reduces to 5 : 6.

45 × 6⁄5 = 54 ✓
35 × 6⁄5 = 42 ✓
55 × 6⁄5 = 66 ✓
40 × 6⁄5 = 48, but the pair printed is 40 : 52 ✗

40 : 52 reduces to 10 : 13, so it is the odd pair → option (a).

Why the others are wrong

(b)
45 : 54 — 45 : 54 divides through by 9 to give 5 : 6, the shape the group is built on, so it cannot be the exception.
(c)
35 : 42 — 35 : 42 divides through by 7 to give 5 : 6. A smaller first term does not make a pair different in kind.
(d)
55 : 66 — 55 : 66 divides through by 11 to give 5 : 6. Its gap of 11 is the largest of the four, but the question separates on ratio, not on gap.

Concept

Odd-pair items are built on one of two things: a difference rule (n → n + k) or a ratio rule (n → kn). Deciding which is in play is most of the work.

The tell here is that the gaps are 12, 9, 7 and 11 — scattered, with no pattern. Scattered differences with numbers of very different sizes usually mean a ratio.

Reduce each pair to lowest terms and the answer is visible without arithmetic: 45 : 54 is 5 : 6, 35 : 42 is 5 : 6, 55 : 66 is 5 : 6, and 40 : 52 is 10 : 13.

Reducing is safer than multiplying, because reducing needs no decision about which direction the rule runs in. A pair either shares the group's lowest terms or it does not.

Key facts

45 : 54, 35 : 42 and 55 : 66 all reduce to 5 : 6.
40 : 52 reduces to 10 : 13, which matches none of the others.
Under a 5 : 6 rule the partner of 40 would be 48, not 52.

Study next

Odd-pair questions settled by reducing every pair to lowest termsTelling a difference rule from a ratio rule by looking at the spread of the gapsPairs built on n → n² ± k, where neither reducing nor differencing works

Common traps

Testing differences first and giving up when 12, 9, 7 and 11 show no pattern.
Reducing 40 : 52 only as far as 20 : 26 and reading it as close enough to 5 : 6. It is 10 : 13.
Assuming the odd pair must be the one with the largest or smallest numbers.

The stem is fixed and carries the digit-splitting NOTE, so only the four pairs change.

Also asked 9 Sep 2024, 12:30, Reasoning Q.18, where 15 : 48, 12 : 39 and 13 : 42 all run n → 3n + 3 and the keyed odd pair is 11 : 35, which would need 36. That rule is a multiplier with a constant added, not the plain ratio this item runs on, so test more than one shape before settling.

Related PYQs

No directly related past PYQ was found.