Let's consider elastic data traffic at flow level on an IP network link with a capacity (speed) of 10 Mbps in the period [0, 20] (time unit: second). The system is empty at time t = 0. New elastic flows arrive at times 2, 4, 6 and 14. The sizes of flow (unit Mbit) are 60, 20, 70 and 10 in the order of arrival. Running contending flows share the link capacity fairly evenly according to PS queue control. a.) Draw a graph that shows the flow's arrival times, the flow's total delays and the number of flows in the system as a function of time t = [0, 20] (i.e. the so-called traffic process). b.) What is the average number of flows during the review period? Hint: your answer should be 1.5. c.) What is the average total delay of the flow?