A). Her distance traveled was (700m + 500m) = 1,200 meters
B). Her displacement was (700m north + 500m south) = 200 meters north
C). Her average speed = (distance covered) / (time to cover the distance)
Speed = (1,200 meters) / (15 seconds)
Speed = 80 meters/second
(Layne is an incredible walker ! That's about 179 miles per hour.)
(She walks 700m in 10 seconds. Usain Bolt runs only 100m in 10 seconds.)
D). Her averge velocity = (displacement) / (time)
Velocity = (200 meters north) / (15 seconds)
Velocity = (13 and 1/3) m/s north
(This is only about 33% faster than Usain Bolt, if he went straight instead of doubling back, and if he could keep it up for 200 meters instead of only 100 meters.)