Exercise 3 solution

Pull the trucker's hitch hard, lock it with two half hitches and tilt the chair to test. Ways it could still fail: the load can shift or settle so the rope goes slack, and the loop or half hitches can slip if the rope is slippery or was not locked off. Other answers are possible.
Takeaway: re-check tension after a load settles, and use straps for anything on a road.