Question on physics below.?

Question

Compute your average velocity in the following two cases: (a) You walk 90.0 m at a speed of 1.06 m/s and then run 90.0 m at a speed of 3.47 m/s along a straight track. (b) You walk for 1.00 min at a speed of 1.06 m/s and then run for 1.41 min at 3.47 m/s along a straight track.

Answer 1

a) Average speed=(Total distance)/(total time).
V=s/t
You can't compute velocity since velocity is a vector and the direction is unknown.

s=90.0+90.0=180.0m
t=90.0/1.06+90.0/3.47= 110.8seconds
v=180/110.8=1.62m/s

b)
v=s/t
s= 1min 60 sec/min 1.06 m/s +1.41min 60sec/min 3.47m/s=357.1 m
t=1min 60 sec+1.41min 60sec=144.6sec
v=357.1/144.6=2.47 m/s