Consider the following work breakdown structure of Chiang's project in days Use the given information, what is the expected (mean) time to complete the activity D? Use the given information, what is the variance of the activity F? Use the given information, what is the expected duration for path A-B-D-E? Used the expected time of an activity to create an activity on node (AON) network diagram, what is the slack of the activity B? Use the given information, What is the expected (mean) time for prolect completion? Use the given information, what is the probability that path A-C-D-F CANNOT be complete in 250 days (Use 2 decimal place for operation and show your result in 0 . *r format)