Problem 3.20 The estimated times and immediate predecessors for the activities in a project at Howard Umrah's retinal scanning company are given in the following table. Assume that the activity times are independent. Immediate Predecessor(s) Immediate Predecessor(s) Activity a Activity a Time (weeks) m b 9 10 13 5 11 18 Time (weeks) m b 7 9 12 4 10 14 This exercise contains only parts a, b, c, d, and e. a) Based on the activity time estimates, the expected times and variance for each of the activities are (round your response to two decimal places): Activity Expected Time Variance b) The expected completion time of the critical path = weeks (round your response to two decimalplaces). The expected completion time of the path other than the critical path = weeks (round your response to two decimalplaces). c) The variance of the critical path = weeks (round your response to two decimal places). The variance of the path other than the critical path = weeks (round your response to two decimal places). d) If the time to complete the activities on the critical path is normally distributed, then the probability that the critical path will be finished in 23 weeks or less = (enter as a probability and round your response to two decimal places). e) If the time to complete the activities on the non critical path is normally distributed, then the probability that the non critical path will be finished in 23 weeks or less = (enter as a probability and round your response to two decimal places)