And where are you stuck with these problems?

Problem 4

a) The formula for average of f(t) on [a, b] is

b) Find the derivative using shortcuts or limits, then plug in.

c) set s(t)=0 then solve for t. Make sure you only accept positive t values for a solution.

d) Plug in the value you find in c) to the derivative function you found in b)

You may benefit more if you show the work you have done so far and explain what you're having problems with, rather than just posting a problem set.

Good luck!