A train of length 110 metre is moving with speed of 36 kilometer/hour. The time taken by the train to cross a bridge of length 132 metres is :

Convert the speed first: 36 km/h × 5/18 = 10 m/s. The train is done crossing only when its last coach has cleared the bridge, so the distance covered is train length plus bridge length: 110 m + 132 m = 242 m. Time = 242 / 10 = 24.2 seconds, which is option B.

• A (13.2 s): This is 132 / 10, using only the bridge length and ignoring the train.
• C (11.0 s): This is 110 / 10, using only the train length and ignoring the bridge.
• D (16.4 s): This implies a distance of 164 m, which matches neither the train, the bridge, nor their sum. It is a miscalculation trap.

The core concept is the crossing formula: total distance = L_train + L_bridge, with speed converted to m/s by multiplying km/h by 5/18. The same logic underlies platform-crossing and tunnel problems, and it is a quick scoring question in the Prelims arithmetic section.

Trap: Aspirants either forget to add the train length or skip the unit conversion and divide by 36 directly.