The length of the bridge, which a train 135 metres long and travelling at 45 km/hr can cross in 30 seconds, is?
Choose the correct answer
A) 76 m B) 178 m C) 240 m D) 187 m E) 176 m

Rationale: "speed = [ 45 x 5 / 18 ] m / sec = [ 25 / 2 ] m / sec time = 30 sec let the length of bridge be x metres . then , ( 135 + x ) / 30 = 25 / 2 = > 2 ( 135 + x ) = 750 = > x = 240 m . answer : c"
Answer: C