Find the speed of the train whose length is 270m? Statement I: A train 270 meter long, passes a bird flying in a straight line at the speed of 9 kmph in the opposite direction in which the train is going, in 12 seconds. Statement II: The train passes another train of length 230 m in 10 sec. Statement III: The speed of the second train is 30m/s.

Statement I alone is sufficient: train length 270m, bird speed 9 kmph (2.5 m/s) opposite direction, time 12 sec. Relative speed = 270/12 = 22.5 m/s. Since opposite direction, train speed = 22.5 - 2.5 = 20 m/s = 72 km/h. Statement II requires unknown direction/speed of other train. Statement III only gives second train's speed without context about first train.