Suppose that you loft the ball with an initial speed of v = 16.2 m/s, at an angle of ? = 49.4° above the horizontal. At this instant your opponent is d = 10.1 m away from the ball. He begins moving away from you 0.400 s later, hoping to reach the ball and hit it back at the moment that it is h = 2.04 m above its launch point. With what minimum average speed must he move?