1) How long does a train 110 metres long running at the speed of 72 km/hr take to cross a bridge 132 metres in length ? A) 9.8 sec B) 12.1 sec C) 12.42 sec D) 14.3 sec E) 14.18 sec Answer: Option BExplanation:Speed $=\left(72\times\frac{5}{18}\right)$ m/sec $=20$ m/sec. Total distance covered $=(110+132)$ m $=242$ m. $\therefore$ Required time $=\left(\frac{242}{20}\right)$ sec = 12.1 sec.
