Answer:
5 m/sec
Explanation:
Let's first convert 1 min 20 sec into only seconds: 1 min = 60 sec --> 60 + 20 = 80 sec
So, Sydney ran 400 meters in 80 seconds. To find out her rate in meters per second, we need to divide 400 by 80: 400/80 = 5
Thus, her average rate was 5 meters per sec.
Hope this helps!