Answer
The average power due to the force is $~~8.0~W$
Work Step by Step
In part (a) we found that the work done on the object by the force is $~~32.0~J$
We can find the average power due to the force:
$P = \frac{Work}{t} = \frac{32.0~J}{4.00~s} = 8.0~W$
The average power due to the force is $~~8.0~W$.