How far does the bullet penetrate and how do i figure this out?

-- You've GOT the kinetic energy of the bullet.

-- That's the amount of work that has to be done to stop it.

-- work = (avg force) x (penetration) and they just gave you the average force.

-- Did you think it would be this easy ?

answer; equivalent to a one(1) horsepower motor;

if they have a finite resultant