Answer
See the graph below for the explanation.
Work Step by Step
The importance of this given area is the total work done on an `object between instants t=t1 and t=t2 by the external forces.
The average power can be found from the mean value theorem which is given as follow
$P= \frac{∫_t1^t2 P (t)dt}{t_{2}-t_{1}} $
On the below graph , the average power is 3 W and the highest power is 6 W.