b) Consider another workshop with two machines that operate independently from one another for Expo() distributed times, each. A single repair facility exists with repair times that are Expo()) distributed. b-i) What is the proportion of time in the long run that the probability that no machine is operating for four different designs: D1) u = 1 = 1; D2) u = 3, 1 = 1; D3) u = 1; 1 = 3; and D4) u = 1 = 2? b-ii) Assume now that at most of the two machines can operate at any given time. What is the long-term proportion of time that no machine is working if u = 1 = 1