Answer
The boat
Work Step by Step
To find the average speed of the car, train, and boat, you divide the total distance traveled by the time it took to travel that distance. This will give you the distance traveled per unit of time. In this case, km per hr (km/hr)
Car: $\frac{\text{360 km}}{\text{6 hr}}=60$ km/hr
Train: $\frac{\text{400 km}}{\text{8 hr}}=50$ km/hr
Boat: $\frac{\text{375 km}}{\text{5 hr}}=75$ km/hr
The fastest average speed was 75 km/hr, which was the boat.