Answer:
26.6m/s
Step-by-step explanation:
Speed = distance/time
When the distance = 200m
Time = 15s
Speed = 200/15
Speed = 13.33m/s
If it returns travelling 2/3rd of the distance, then the new distance will be:
2/3 × 200
New Distance = 400/3 m
Time taken = 10s
Speed during this period = 400/3 × 1/10
= 400/30
= 40/3
= 13.3m/s
Average speed during the entire trip = 13.3+13.3 = 26.6m/s