Cameron is out running in a straight path for an hour. His distance (in kilometers) from home t hours after leaving is given by the formula s(t) = 12(t-t2), for 0 t 1. His average velocity for the hour-long run is 0 km./h., since s(1) - s (0) 1-0 = 0-0 1 0 = 0. What is Cameron's average velocity (in km./h.) during the first half-hour of his trip?