3. A group of hikers sets out from point A, proceeds to B, then to C, and finally to D. The entire trip takes 6.0 h. N B 8.0 km C W E 2.0 km A 8.0 km (a) Determine the hikers' average speed for the trip. (b) What is the hikers' final displacement relative to their initial position? (c) If the hikers release a homing pigeon upon their arrival at point D and the bird returns to point A 30 min later, what is the bird's average velocity during the flight?