SSC CGL 2024 Tier-I · 9 September 2024, Shift 3 · General Intelligence and Reasoning · Question 4 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.

Three of the following numbers are alike in a certain way and one is different. Pick the odd one out. (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)36 – 84
(b)33 – 72
(c)66 – 154
(d)72 – 168

Answer

Why

Correct — B. Test each pair as a ratio of its two whole numbers.

36 – 84: 84 ÷ 36 = 7/3
66 – 154: 154 ÷ 66 = 7/3
72 – 168: 168 ÷ 72 = 7/3

Rule: the second number is 7/3 of the first — divide by 3, then multiply by 7.

Apply it to the remaining pair:
33 ÷ 3 = 11, and 11 × 7 = 77, but the pair prints 72.

33 – 72 is the one pair that breaks the rule, so it is option (b).

Why the others are wrong

(a)
36 – 84 — 36 – 84 obeys the rule: 36 ÷ 3 = 12 and 12 × 7 = 84. It sits with the group of three, so it cannot be the odd one out.
(c)
66 – 154 — 66 – 154 obeys the rule: 66 ÷ 3 = 22 and 22 × 7 = 154. The larger numbers make it look unlike the others, but the ratio is the same 7/3.
(d)
72 – 168 — 72 – 168 obeys the rule: 72 ÷ 3 = 24 and 24 × 7 = 168. Both its numbers are double those of 36 – 84, and doubling leaves a ratio unchanged.

Concept

In an SSC odd-one-out on number pairs the relation is arithmetic on the whole numbers — a ratio, a difference, or a multiple plus a constant.

The bracketed note in the stem exists to stop you splitting a number into its digits. 33 is thirty-three, not a 3 and a 3.

Ratio is the first thing to test whenever the second number is a small multiple of the first. Here every second number is between two and three times its partner, so reduce all four pairs to lowest terms and compare.

Three pairs reduce to 3 : 7. The fourth reduces to 11 : 24, and 3 : 7 scaled to a first term of 11 would be 11 : 25.67 — close enough to survive a careless glance.

Key facts

36 : 84, 66 : 154 and 72 : 168 all reduce to 3 : 7.
33 : 72 reduces to 11 : 24, which is not 3 : 7.
The stem's note keeps all working on the whole numbers, so no digit may be handled separately.

Study next

Odd-one-out on number pairs decided by ratio rather than by differenceReducing a pair to lowest terms quickly using the HCFRelations of the form second = a x first + b

Common traps

Testing differences first — 48, 39, 88 and 96 are all different, so difference decides nothing here.
Splitting 33 into 3 and 3, which the stem's note rules out.
Stopping once two pairs agree, when the odd one is only visible after all four are checked.

SSC prints a standing note on these items telling you to operate on the whole number and never on its digits. Read it, because it closes off the fastest wrong method.

Reduce every pair to lowest terms before you look at the options.

Related PYQs

No directly related past PYQ was found.