Average speed, average velocity for a road trip

[Iron_Man_123]

Homework Statement

[/B]
I'm very stuck at answering parts (c) and (d)

Homework Equations

speed = Distance/Time

The Attempt at a Solution

 

[Jamison Lahman]

I haven't worked the problem myself, but I am not sure your solutions to parts a and b are correct. Does it make sense to have average velocities higher or lower than both velocities? Perhaps this is why you're struggling on c and d.

 

[haruspex]

In both a) and b) you got confused between the half (time or distance) and the whole.
For d), what is the difference between speed and velocity?