Final answer:
The average velocity of the speedboat is 10 m/s.
Step-by-step explanation:
To calculate the average velocity of the speedboat, we need to find the change in position and divide it by the change in time. In this case, the speedboat uniformly increases its speed from 25 m/s west to 35 m/s west. The change in speed is 35 m/s - 25 m/s = 10 m/s. If we assume the change happens in a time interval of 1 second, then the average velocity would be 10 m/s.