the young folk decide to ride the (the Chaperones opt to watch from the comfort of the ground). At its maximum height, the ride reaches 65 m above the ground. When one boy reaches the top of the tower, his gum falls out of his mouth. The height of the gum can be given by the mathematical model: h=65-4.9t^2

where t is in seconds and h is measured in metres.

a. Find the average velocity of the gum on the intervals 2 < or equal t < or equal 3 and 2 < or equal t < 2.1

b. Find the instantaneous velocity when t=2