What is your average speed?

Question

You run 100 meters at a speed of 5.0 m/s and then you walk 100 meters at a speed of 1.0 m/s. What is your average speed for this entire exercise period?

Answer 1

d - distance
v - speed
t - time

d = st
t = d / v
v = d / t
~~~~~~~~~

d₁ = 100 m
v₁ = 5.0 m/s   
t₁ = 100 / 5 = 20 (seconds)

d₂ = 100 m 
v₂ = 1.0 m/s
t₂ = 100 / 1 =100 (seconds) 

Average speed 
v = (d₁ + d₂) / (t₁ + t₂)
v = 200 / 120 = 5 / 3 ≈ 1.7 m/s