The length of the bridge, which a train 120 meters long and travelling at 45 km/hr can cross in 30 seconds, is:  Choose one.
A) 239 B) 277 C) 255 D) 88 E) 232

Rationale: "speed = ( 45 * 5 / 18 ) m / sec = ( 25 / 2 ) m / sec . time = 30 sec . let the length of bridge be x meters . then , ( 120 + x ) / 30 = 25 / 2 = = > 2 ( 120 + x ) = 750 = = > x = 255 m . answer : c"
Answer: C