Answer:
4.25 m/s
Explanation:
They walked the first distance at 5.50 m/s, then the same distance at 3 m/s.
Since the distances are equal, the average speed is simply the average of 5.50 and 3.
(5.50 + 3) / 2 = 4.25
Her average speed over the entire trip is 4.25 m/s.