Answer:
96 m
Step-by-step explanation:
The average velocity over those 4 seconds is the velocity after 2 seconds:
30 m/s -(2 s)(3.0 m/s^2) = 24 m/s
The displacement is the product of this average velocity and the duration of the acceleration:
d = (24 m/s)(4 s) = 96 m
The boat covered 96 m while being accelerated.