A trip to a destination is made in the following way:
a) 550 km by train at an average speed of 55 km/h
b) 4500 km by plane at an average speed of 500 km/h
c) 400 km by boat at an average speed of 25 km/h
d) 55 km by auto at an average speed of 35 km/h
What is the average speed for the entire journey?
1
3300 km/h
2
9600 km/h
3
121(64/25) km/h
4
150(135/256) km/h