Help! How would I ans this rates of change question?

Question

If a ball is thrown straight up into the air with an initial velocity of 80 ft/s, its height in feet after seconds is given by

y = 80t - 16t². Find the average velocity (i.e. the change in distance with respect to the change in time) for the time

period beginning when = 1 and lasting..

a) 0.5 secs

b) 0.1 secs

c) 0.01 secs

d) 0.0001 secs

based on those results in a) to d), guess what the instantaneous velocity of the ball is when t=1?

Answer 1