SSC CGL 2025 Tier-I · 17 September 2025, Shift 3 · General Intelligence and Reasoning · Question 17 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

A train 180 m long passes a point in 12 s. Find the speed of the train.

(a)45 km/h
(b)54 km/h
(c)60 km/h
(d)72 km/h

Answer

Why

Correct — B.
Rule: passing a point, a train covers just its own length.

Distance = 180 m, time = 12 s
Speed = 180 ÷ 12 = 15 m/s
Convert: 15 × 18⁄5 = 54 km/h → option (b).

Why the others are wrong

(a)
45 km/h — 45 km/h is 12.5 m/s, which covers only 150 m in 12 s. The train is 180 m long, so it must be faster.
(c)
60 km/h — 60 km/h is 16⅔ m/s, which covers 200 m in 12 s, 20 m more than the train's length.
(d)
72 km/h — 72 km/h is 20 m/s, which covers 240 m in 12 s. That suits a 240 m train, not a 180 m one.

Concept

A train passing a point (a pole, a signal, a standing man) has cleared it when its tail reaches the point, so the distance covered is exactly the train's length. Passing a platform or bridge, the distance becomes train length + platform length.

Then convert. 1 km/h = 1000 m ÷ 3600 s = 5⁄18 m/s, so m/s × 18⁄5 gives km/h.

Multiplying by 18⁄5 is the same as multiplying by 3.6, which is quicker with decimals: 15 × 3.6 = 54.

Key facts

Passing a point: distance = length of the train.
Passing a platform or bridge: distance = train length + platform length.
m/s to km/h: multiply by 18⁄5 (3.6). km/h to m/s: multiply by 5⁄18.

Study next

Trains crossing a platform or bridge, where the two lengths addTwo trains crossing each other: relative speed in opposite and same directionsFinding a train's length from its speed and crossing time

Common traps

Stopping at 15 and forgetting to convert m/s to km/h
Multiplying by 5⁄18 instead of 18⁄5, which gives about 4.2

21 Sep 2025, 16:00, Reasoning Q.23 sets the same case: a 120 m train crosses a man in 6 s, so 20 m/s, keyed 72 km/h.

24 Sep 2024, 12:30, Quant Q.5 extends it to two trains running towards each other, where both lengths add (132 + 108 = 240 m) and so do the speeds.

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