A 110 m long train crosses a tree in 3 s. How long will take to cross 165 m long platform and 135 m long bridge, if platform and bridge are at a distance of 30 m?

The distance covered by the train to cross the platform and bridge
= Length of the platform + Length of bridge + Distance between platform and bridge + Length of the train
= 165 + 135 + 30 + 110 = 440 m
Speed of train = 110 /3 m/s
∴ Required time taken = 440/(110/3) = 12 s