A monkey climbs up a slippery pole for 3 seconds and subsequently slips for 3 seconds. Its velocity at time (t) is given by v(t) = 2t (3-t); 0< t < 3 and v (t)=–(t–3)(6–t) for 3 < t < 6 s It repeats this cycle until it reaches the height of 20 m.At what time is its average velocity maximum?