If a ball is thrown into the air with an initial velocity of 48 ft/s, its height in feet after t seconds is given by y = 48t − 16t2. (a) Find the average velocity of the ball (in ft/s) for the time interval beginning at t = 2 and lasting for each of the following. 0.5s, 0.1s, 0.05s, 0.01s