Refer to attachment for your answer
Each electron has a charge of

In this problem, the total charge is

Therefore, the number of electrons contained in this total charge will be given by the total charge divided by the charge of a single electron:

Answer:
Power = Work / Time
P = 400 kg * 9.8 m/s * 4.5 m / 3600 sec = 4.9 J/s = 4.9 Watts
Also, 4.9 Watts / (746 Watts / Horsepower) = .0066 Hp