please slove it in a text.

A partially solved PERT problem is detailed in the table below. Times are given in weeks. a) Calculate the expected duration (D), and variance of each activity. b) Caiculate ES, EF, LS, LF, S for each activity. c) Which activities form the critical path? d) What is the estimated time of the critical path? e) If the project is due to be completed in 40 weeks, what is the probability that the project will be completed on the due date? f) If the project manager wants at least a 95% probability that the project will be completed on the due date, what is the shortest project due date that will satisfy the manager? c) Which activities form the critical path? d) What is the estimated time of the critical path? e) If the project is due to be comploted in 40 weeks, what is the probability that the project will be completed on the due date? f) If the project manager wants at least a 95% probability that the project will be completed on the due date, what is the shortest project due date that will satisly the manager