 Initial PERT network:
 The latest time that
F, G and H
can finish without
lengthening the duration of the project =
18
Therefore:
 LF(F) = 18
 LF(G) = 18
 LF(H) = 18

That means that the
latest time that
G and H
can start without
lengthening the duration of the project
are:
 EF(F) = 18 − 3 = 15
 EF(G) = 18 − 6 = 12
 EF(H) = 18 − 2 = 16

Therefore:
 The latest time that G must
start = 12
Therefore: the latest time that D
must finish without
pushing the start of G further =
12
Therefore:
That means that the
latest time that
D
must start without
lengthening the duration of the project
is:
(Similar reasoning hold for
activity E)
Therefore:
 The latest time that:
 D must
start = 9
 F must
start = 15

Therefore: the latest time that B
must finish without
pushing the start of D or F
further =
9 !!!
Therefore:
That means that the
latest time that
D
must start without
lengthening the duration of the project
is:
(Similar reasoning hold for
activity C)
Therefore:
 The latest time that:
 B must
start = 6
 C must
start = 3

Therefore: the latest time that A
must finish without
pushing the start of B or C
further =
3 !!!
Therefore:
That means that the
latest time that
D
must start without
lengthening the duration of the project
is:
Result: