Please answer every part!

3.20 The estimated times and immediate predecessors for the activities in a project at George Kyparis's retinal scanning company are given in the following table. Assume that the activ- ity times are independent. TIME (WEEKS) ACTIVITY IMMEDIATE PREDECESSOR m b A 9 10 11 9 4 B 4 10 16 A 9 10 11 D B 5 8 11 a) Calculate the expected time and variance for each activity. b) What is the expected completion time of the critical path? What is the expected completion time of the other path in the network? c) What is the variance of the critical path? What is the variance of the other path in the network? d) If the time to complete path A-C is normally distributed, what is the probability that this path will be finished in 22 weeks or less? e) If the time to complete path B-D is normally distributed, what is the probability that this path will be finished in 22 weeks or f) Explain why the probability that the critical path will be fin- ished in 22 weeks or less is not necessarily the probability that the project will be finished in 22 weeks or less. Px less