# Michelle

## Michelle

I. A1. Expected Completion Time
ECT is derived using the formula which obviously gives more weight to the “probable” time estimate:

Where a = Optimistic time
b = Probable time to complete
m = Pessimistic time
Before allowing for concurrent activities. those that can proceed on parallel tracks, as it were, ECT for the entire project is shown by Table 1 (overleaf) below as 68 ½ weeks:

Table 1: First Estimate of ECT

a
m
b
Calculation
Expected Time to Complete (weeks)

A
2
3
4
(2+(4x3)+4)/6
3
B
5
6
13
(5+(4x6)+13)/6
7
C
3
4
8
(3+(4x4)+8)/6
4.5
D
10
11
15
(10+(4x11)+15)/6
11.5
E
4
5
6
(4+(4x5)+6)/6
5
F
8
10
12
(8+(4x10)+12)/6
10
G
4
6
11
(4+(4x6)+11)/6
6.5
H
8
10
18
(8+(4x10)+18)/6
11
I
3
6
12
(3+(4x6)+12)/6
6.5
J
2
3
7
(2+(4x3)+7)/6
3.5
TOTAL

68.5

But the fact is, there are many possibilities for concurrent project activity. Task B, for instance, can be triggered by project start and has no start-to-finish link with Task A. Task D itself does not depend on tasks A and C being completed; it can proceed as soon as B is done. When one runs through all the concurrent stages, net elapsed time can really collapse to 35 weeks (Table 2 below). Given ECT = ES + t, as well, Table 3 (overleaf) displays the calculations and outcomes which compress project completion to 30 weeks.

Table 2: ECT Based on "Probable Time to Complete" and Employing Forward Pass
Preceding Activity
Probable Time to Complete
(weeks)
Earliest Start
Earliest Finish
START

A
START
3
0
3
B
START
6
0
6
C
A
4
3
7
D
B
11
6
17
E
C
5
7
12
F
B
10
6
16
G
F
6
16
22
H
D,E
10
17
27
I
G
6
22
28
J
H,I
3
28
31
END

TOTAL
64

31

II. A1a. Schedule Variance
Conceding a degree of uncertainty for each task and employing the formula for variance of activity time:

Where a = optimistic time and b =...