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