i'll help you out with #4

Take the derivative of the position function

B) v(1.5) = ?

C) v(0) = ?

D) v(t) = 24

For the 1st question take the derivative of the function and set it to 0 to find your critical points. Your max and min will occur at your critical points if there are any. Use the 1st or 2nd derivative test to see if it is a max or min.