The position in feet of a race car along a straight track after t seconds is modeled by the function. s (t) = 812 - (+3 (a) Find the average velocity (in ft/s) of the vehicle over the following time intervals to four decimal places. (1) [4, 4.1] it /s (ii) [4, 4.01] ft /s (iii) [4, 4.001] ft / s (iv) [4, 4.0001] ft / s (b) Use part (a) to draw a conclusion about the instantaneous velocity (in ft/s) of the vehicle at t = 4 seconds. (Round your answer to t ft /s Tutorial Additional Materials