Project management: probability of completing all activities

I want assistance with c(i) and c(ii) only in following question.

The project of building a backyard swimming pool consists of eight major activities and has to be completed within 19 weeks. The activities and related data are given in the following table:

Activity Immediate predecessor Activity time (weeks)
A - 3
B - 6
C A 2
D B,C 5
E D 4
F E 3
G B,C 9
H F,G 3

a. Draw a network diagram for this problem.
b. Determine the critical path and the expected project completion time.
c. Assume the project variance is 4 weeks.
i. What is the probability that all the activities are completed within 19 weeks?
ii. When is the due date if there is a 90% of completing all the activities?

Here is what I have done so far.

a) To calculate the probability in c(i) question is to put

P(complete) = P (x < 19)
P (z< 21-19/ square root 4)
P (z<2/2)
P (z <1)
0.8413

So it is 84.13%. Is this correct?

b) To calculate expected date of completion in c(ii) is to calculate for each of the possible task which is

As per your message you want assistance with c(i) and c(ii) only, so I will restrict this response to these.

Since we do not have information on optimistic, pessimistic and most likely time estimates for various tasks, we would consider expected time as the time taken on critical path B-D-E-F-H (rather than the sum of all the expected durations on the critical path), that is, 21 weeks.

Expected Duration of project completion = Te = 21 weeks
Project variance ...

Solution Summary

As question is asking for assistance with c(i) and c(ii) only, this solution addresses only these two.
Since the interpretation of "When is the due date if there is a 90% of completing all the activities?" is not clear, this solution considers that it is asking us to compute the due date if there is 90% of completing all the activities in 19 weeks.

The time to complete a project may be shown in a chart; however, the sequence of activities for completing the project may not be shown in a chart. Do you agree or disagree with this statement? Defend your response. 100 words.

Suppose the length of critical path in a project is 50 days. The probability of completing the project within 50 days is:
Less than 50%
Greater than 50%
Equal to 50%
Can not be determined from the above data

Given an auditing project with the following activities,
Using the critical path, find:
(a)The probability of completing this project in 12 weeks (or less), as the client desires.
(b)The probability of completing this project in 13 weeks (or less).
(c)The probability of completing this project in 16 weeks (or less),

Please see the attached file.
PROBLEM:
In the Marketing Department at LRH Financial, project managers do not have operational responsibilities. They manage multiple projects and leverage people from various teams within the marketing department. Because you will be leveraging individuals on a part-time basis from several

Given the following table:
1. Draw the network diagram
2. Determine the critical path
3. Calculate the expected duration and variance for each acitivity
4. Calculate the expected duration and variance of the critical path
5. Find the probability of completing the project in:
a. Less than 22

Please view the attached file to see the tables laid out properly.
1.) Given the following network project:
Activity Estimated Time (mo.) Immediate Predecessor
A 10 -
B 12 -
C 15 -
D 18 A
E 7 C
F 9 B,C
a. Develop a network diagram.
b. How long will it take to complete the project?
c. Which activit

A few moments ago, Fred (one of your other key marketing specialists) handed you his resignation letter. He has accepted a similar opportunity with a competitor. His last day with LRH is in 3 days, and he is unwilling to stay any longer. He starts his new job right away and would like some time off between jobs. Your immediate r

I am looking for some help on this project management problem.
Since it's difficult to post the information in here please see the attachment.
Example of how it is done below is attached as the PDF's, This is all the data that I was given for the problem. I only attached the examples as the PDF's, the word attachment is the