a)
Explanation:The initial speed, u = 0 m/s (The boat starts from rest)
Th final speed, v = 7 m/s
The time, t = 15 s
To find the average acceleration, use the equation below
[tex]\begin{gathered} a=\frac{v-u}{t} \\ \\ a=\frac{7-0}{15} \\ \\ a=\frac{7}{15} \\ \\ a=0.47\text{ m/s}^2 \end{gathered}[/tex]The acceleration of the boat is in the direction of the motion
b) If the boat continues with the same acceleration for another 6 seconds:
Total time, t = 6 + 15 = 21 s
Speed = Acceration x time
Speed = 0.47 x 21
Speed = 9.87 m/s