Please show all steps in a simple way

A project has the specifications as shown in the following table. a Optimistic time b 11 11 11 Pessimistic time m Most likely time. All times are in months Activity Immediate Predecessors a b m Mean St. Dev. Variance A None 2 8 15 None 3 3 C A 7 12 8 D B. C W 5 4 B 2 10 F D 10 18 14 G E, F 4 10 7 a. Develop a project network diagram. (Marks 4) b. Determine the expected project completion time. (Marks 4) c. Identify the critical activities. (Marks 4) d. Calculate the standard deviation of the expected project completion time. (Marks 2) e. What is the probability that the project will be completed one month earlier than the expected completion time? (Marks 3) f. What is the probability that the project will be delayed by one month from its expected completion time? (Marks 3) g. You must show all the workings or steps of your solution. Merely answer does not carry any mark. h. This assignment will be marked out of 20 and then converted to out of 5