Path
mean
Path

time
Specified
=
z
ACE
Z=(24  20.5)/1.118=3.13
P(Z<3.13)=0.9991
DFG
Z=(24  21.5)/1.344=1.86
P(Z<1.86)=0.9686
BHI
Z=(24  19.5)/0.726=6.19
P(Z<6.19)=1.0000
Z
24
Probability
ACE
Z=(2120.5)/1.118
=0.45
P(Z<0.45)
=0.6736
DFG
Z=(2121.5)/1.334
=0.37
P(Z<.37)
=0.3557
BHI
Z=(2119.5)/0.726
=2.07
P(Z<2.07)
=.9808
Z
21
Probability
What is the probability that the project can
be completed in
21days or less
?
(
29
2
2
6

=
o
p
t
t
σ
Probability=.6736 x.3557 x .9808 = 0.235
Probability=0.9991*0.9686*1=0.967
5
7/819
c. Suppose it is now the end of the seventh day and that activities A and B have been
completed while activity D is 50 percent completed.
Time estimates for the completion
of activity D are 5,6 and 7.
Activities C and H are ready to begin.
c. On the 8th day,
the network could be reviewed as
follows:
1
5
3
7
8
6
e (6.33)
f (6)
d
′
(6)
g (3.5)
i (6.83)
h (4.17)
c (8.17)
8
th
day
*Assume it is the beginning of the 8th
day
Replace d by d
′
and merge
nodes (2) and (4) with (1).
d
′
: te = 6:
σ
2 = 4/36
7 days were used to complete
activities a, b and one half of d. In
the modified network
Path
Expected
Duration
from 8th day
Expected
duration from
the start of the
project
Varia
nce
1
.
c–e
14.50
14.50 + 7 = 21.5
41/36
2
.
d
′
–
f–g
15.5
15.5 + 7
=
22.5
33/36
3
.
h–i
11
11 + 7 = 18
10/36
6
Path
Standard Dev.
Z
24
Probability (24)
1.
c–e
1.0672
24 –
21.5
= 2.343
.9904
1.067
2
2.
d
′
–f–g
0.9574
24 –
22.5
= 1.567
.9418
0.957
4
3.
h–i
0.5270
24 –
18
= 11.384
1.0000
0.527
.9904 x .9418 = .9328
Path
Z
21
Probability (21)
1.
c–e
21 – 21.5
= –0.469
0.3192
1.0672
2.
d
′
–f–g
21 – 22.5
= –1.567
0.0582
0.9574
3.
h–i
21 – 18
= 5.692
0.527
.3192 (.0582) = 0.0186
7
1
4
3
2
5
6
7
8
9
10
11
3.00
2.00
6.00
5.00
7.00
2.00
3.00
4.00
5.00
4.00
6.83
0.00
3.00
0.00
3.00
1
6.00
8.00
3.00
5.00
2
8.00
11.00
5.00
8.00
5
3.00
9.00
3.00
9.00
3
9.00
11.00
9.00
11.00
6
11.00
15.00
11.00
15.00
8
4.00
9.00
3.00
8.00
4
9.00
16.00
8.00
15.00
7
16.00
20.00
15.00
19.00
10
15.00
20.00
15.00
20.00
You've reached the end of your free preview.
Want to read all 9 pages?
 Spring '12
 CharoenR.
 Management, Standard Deviation, Critical path method, slack