Activity		Estimated duration (weeks)
i	j	to	tm	tp
1	2	2	3	5
1	3	4	9	14
1	4	2	8	12
2	5	1	1	1
3	5	2	5	14
4	6	2	8	10
5	6	3	9	15

i) Draw project network
ii) Find expected duration, standard deviation and variance of all activities.
iii) Calculate the variance of the project duration.
iv) What is the probability that the project will be completed 3 weeks earlier than the expected date?