Samir is biking along a straight path, starting in the s(0) northbound direction. Here is a graph that shows -8 Samir's position s (in kilometers) at time t (in hours). 7 -6 (a) What is Samir's average velocity in the time from t = 1 to t = 4? -4 2 12 3 4 5 6 7 8 (b) What is Samir's velocity at time t = 7.5 and in what direction is he moving? (c) By looking at the graph, determine whether Samir is speeding up or slowing down at time t = 6.1. Explain your reasoning