138 | 1. GETTING ORGANIZED FOR VALUE-BASED HEALTHCARE DELIVERY 8. A team of trauma surgeons is concerned about the time it takes to receive blood for transfusions. They have identified all the activities involved in the process, their precedence relationships, and their durations. a. Draw the AON network. b. Determine the time estimate for each activity. c. Find the ES, EF, LS, LF, and S for each activity and determine the critical path. How long is this process expected to last? d. What is the probability of completing this process in 180 minutes and in 220 minutes? e. What is the probability that the process will take longer than 200 minutes? Pessimistic Immediate Optimistic Most Likely Activities Time Time Predecessors Time (min) 0.5 7 1.5 A. Blood transfusion is ordered B. Phlebotomist draws blood A 30 38 46 sample C. Sample is sent to lab B 12 16 20 D. Nurse places blood band on B 2 4 6 patient E. Blood bank identifies blood type and checks for antibod- C 12 15 18 ies F. Blood bank cross-checks patient's plasma against red E 25 30 41 blood cells in blood bank G. Blood bank notifies nursing floor when blood is ready F 2 and sends to floor 5 8 H. Blood is checked by two nurses to confirm patient D,G date of birth 18 21 24 1. Blood transfusion is per- formed H 50 60 76 9. Bradley Park Hospital's environmental services team wants to reduce patient roo turnover times without sacrificing safety and room cleanliness. Their first ta involves identifying all the activities necessary to clean and disinfect a room af patient discharge and their respective durations (in minutes). Their efforts led to following network diagram. a. What is the time estimate for each activity? b. Find the ES, EF, LS, LF, and S for each activity and determine the critical p How long does it take to clean and disinfect a room? c. What is the probability of completing the room cleaning and disinfection pro in 63 minutes and in 67 minutes? d. What is the probability that the process will take longer than 60 minutes