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.