Please help, don't understand the steps to completing this question...

If a ball is thrown into the air with a velocity of 40 ft/s its height in feet t seconds later is given by y=40t-16t^2.

a) find the average velocity for the time period beginning when t = 2 and lasting (i) .5 secs (ii) .1 secs (iii) .of secs (iv) .01 secs

b) Estimate the instantaneous velocity when t = 2

Question

Please help, don't understand the steps to completing this question...

If a ball is thrown into the air with a velocity of 40 ft/s its height in feet t seconds later is given by y=40t-16t^2. 

a) find the average velocity for the time period beginning when t = 2 and lasting (i) .5 secs (ii) .1 secs (iii) .of secs (iv) .01 secs

b) Estimate the instantaneous velocity when t = 2

anonymous · Answer

compute 
$$\frac{f(2.5)-f(2)}{.5}$$ for the first one
others are similar
use a calculator

anonymous · Answer

Where are these numbers coming from? I still don't get it

anonymous · Answer

Satellite is right. and numbers come from the question itself. You have a period of time which begins at 2 and lasts for some given x (0.5, 0.1 ...).