Answer
The average power of the force is $~~0.55~hp$
Work Step by Step
In part (a), we found that the work done by the force in ten minutes is $~~(1.83\times 10^5)~ft\cdot lb$
We can find the average power:
$P = \frac{Work}{t}$
$P = \frac{(1.83\times 10^5)~ft\cdot lb}{600~s}$
$P = 305~ft\cdot lb/s$
$P = (305~ft\cdot lb/s)\times (\frac{1~hp}{550~ft\cdot lb/s})$
$P = 0.55~hp$
The average power of the force is $~~0.55~hp$.