If a ball is thrown straight up into the air with an initial velocity of $50$ ft/s, its height in feet after $t$ second is given by $y = 50 t - 16 t^2$. Find the average velocity for the time period beginning when $t = 2$ and lasting
(i) $0.5$ seconds

(ii) $0.1$ seconds

(iii) $0.01$ seconds

Finally based on the above results, guess what the instantaneous velocity of the ball is when $t =2$.