As part of his journey, a person travels 120 km at 80 km/h, the next 100 km at 40 km/h, and comes back to the starting point at 75 km/h. The average speed of the person throughout the journey (approximately) is:
1
63.46 km/h
2
58.74 km/h
3
68.15 km/h
4
49.58 km/h