There is a fly and there is a train. Train runs at 60km/hr and fly flies at 30km/hr.
The fly starts flying from a point X towards the coming train, touches it, and then fly back to X again. It again flies back to train..touches it and den fly back to X. This whole continues till the train reaches X.
The initial distance between train and X is 1km.
How much distance the fly travelled in the direction of train?