A carrier train, when it is 100 km away from the station, going at a constant speedof 70 kph towards the station. At this instant a fast bird from its engine flies towards the station at 100 kph net speed.When the bird gets to the station, it turns back and flies again towards the train, when it reaches engine, it again turns and heads towards the station. If bird keep son flying in such a manner, find the distance travelled by the bird before train reaches the station ? How many trips, it made in this duration between station and the train ?