To calculate the average velocity of the speedboat, we need to use the formula for average velocity:
\[ \text{Average Velocity} = \frac{\text{Total Displacement}}{\text{Total Time}} \]
In this case, the boat travels a total distance (which is also the displacement, since it moves in a straight line) of 20 meters in a time of 18 seconds.
\[ \text{Average Velocity} = \frac{20 , \text{m}}{18 , \text{s}} \approx 1.11 , \text{m/s} \]
The average velocity is approximately +1.11 m/s (it's positive because the boat moved away from the dock in a defined positive direction).
So, the correct response is +1.11 m/s (plus 1.11 meters per second).