Question

Find a Person's Average Speed of Kilometre per Hour
One person running 150 km for 50 km/hour speed and return that person 30 km/hour. So what is the average speed of km/hour person?

Answer 1

Known
v₁=50 km/hour
v₂=30 km/hour
S₁=150 km
S₂=150 km
Asked: Δv?
Answer:
Look at the image:

from that we know :
ΔS=S₁+S₂ =150+150 =300 =150 km 
            2               2           2
So for average speed is:
Δv=v₁+v₂ =50+30 =80 =40 km/hour from start to finish.
          2            2        2

Okay solved .