The downstream speed of a boat is 25% more than its upstream speed. The boat takes 3.2 hours to travel 57.6 km upstream. Which of the following statement(s) is or are true according to the information?
I. Speed of stream is 3 km/h
II. Time required to cover 108 km in still water is 4 hours
III. Time needed to go 72 km downstream and return upstream is 7.2 hours