The time estimates for the activity of the PERT diagram are given in the table below. Calculate the expected time, variance, and standard deviation for each activity

The time estimates for the activity of the PERT diagram are given in the table below. Calculate the expected time, variance, and standard deviation for each activity
 

Activity	to	tm	tp
1-2	1	2	3
2-3	8	10	12
2-4	2	4	6
2-5	3	5	7
3-6	4	5	6
4-6	7	8	9
5-7	6	8	10
6-7	1	4	7

 

 

Solution:

Activities	to	tm	tp	`t_e=\frac{t_o + 4t_m + t_p}{6}`	`S.D=\frac{t_p - t_o}{6}`	`Variance =(\frac{t_p - t_o}{6})^2`
1-2	1	2	3	2	1/3	1/9
2-3	8	10	12	10	2/3	4/9
2-4	2	4	6	4	2/3	4/9
2-5	3	5	7	5	2/3	4/9
3-6	4	5	6	5	1/3	1/9
4-6	7	8	9	8	1/3	1/9
5-7	6	8	10	8	2/3	4/9
6-7	1	4	7	4	1	1