The length of the bridge, which a train 130 metres long and travelling at 54 km/hr can cross in 30 seconds, is:
Pick one
A) 200 m B) 225 m C) 320 m D) 250 m E) 240 m

Rationale: "speed = [ 54 x 5 / 18 ] m / sec = [ 15 / 1 ] m / sec time = 30 sec let the length of bridge be x metres . then , ( 130 + x ) / 30 = 15 = > ( 130 + x ) = 450 = > x = 450 - 130 = 320 m answer : c"
Answer: C