SSC CGL 2024 Tier-I · 17 September 2024, Shift 3 · General Intelligence and Reasoning · Question 8 of 98

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.

Three of the following four options are alike in a certain way and thus form a group. Which is the one that does NOT belong to that group? (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/subtracting/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)118 – 93 – 161
(b)86 – 41 – 38
(c)52 – 36 – 56
(d)33 – 15 – 12

Answer

Why

Correct — B. Differences lead nowhere here; the link is between the outer numbers and the middle one.

Rule: first + third = 3 × middle.

118 + 161 = 279 = 3 × 93
52 + 56 = 108 = 3 × 36
33 + 12 = 45 = 3 × 15

Option (b) gives 86 + 38 = 124, while 3 × 41 = 123. It misses by one, so option (b) is the triple that does not belong.

Why the others are wrong

(a)
118 – 93 – 161 — 118 + 161 = 279, and 279 ÷ 3 = 93, the middle number exactly. The rule holds, so this option stays inside the group of three.
(c)
52 – 36 – 56 — 52 + 56 = 108, and 108 ÷ 3 = 36, the middle number. Its numbers are the closest together of the four, but closeness is not the grouping rule.
(d)
33 – 15 – 12 — 33 + 12 = 45, and 45 ÷ 3 = 15. These are the smallest numbers on offer, which tempts a quick eye, but size is not what separates the group.

Concept

When an odd-one-out gives three numbers per option, test rules that use all three at once.

Differences are the usual first attempt and they fail here: 118 − 93 = 25 while 52 − 36 = 16, with nothing in common.

The rule that works ties the outer pair to the middle: first + third = 3 × middle, or equivalently the middle number is one third of the sum of the other two. Once the rule is fixed on two options, the remaining two decide the question in a few seconds.

The outlier is a near miss, not an obvious break. 124 against 123 is a difference of one, so this question rewards exact arithmetic and punishes rounding or eyeballing.

Key facts

The rule in words: the middle number is one third of the sum of the outer two.
Options (a), (c) and (d) satisfy the rule exactly, while option (b) gives 124 where 123 is required.
The printed NOTE bars digit-splitting, so 118 may not be read as 1, 1 and 8.

Study next

Odd-one-out on number triples, tested with sum-and-multiple rules rather than differencesThe first + third = k × middle family, with k found on one option and confirmed on a secondNear-miss options that fail by 1, which reward exact arithmetic over estimation

Common traps

Abandoning the question after differences fail, instead of trying a sum rule.
Rounding 124 to 123 at a glance, which erases the entire distinction.
Expecting the outlier to stand out by size or parity when all four triples look alike.

SSC sets this four-option odd-triple stem at Reasoning Q.6 on 17 Sep 2024, 09:00 and Q.1 on 10 Sep 2024, 16:00. Both carry the same NOTE barring digit-splitting, so 118 stays 118.

Related PYQs

No directly related past PYQ was found.