Use these activity durations (that have been estimated at 90%) and precedence requirements to create two project schedules — a traditional schedule based on early start times and a critical chain schedule with buffers

Activity Time Predecessor
A 8
B 15
C 19 B
D 12 C
E 3 C
F 16 A
G 12 F
H 16 E
R 7 D
J 16 G, H
K 12 R
L 8 J, K

The traditional case is exhibited immediately below. The Gantt chart shows no buffers and the project finishes at time 77.

The first step in creating the critical chain schedule is to reduce activity durations to a respectable 50% likelihood from their bloated 90% likelihood estimates. The new activity durations are as follows:

Activity Time Predecessor
A 4
B 7.5
C 9.5 B
D 6 C
E 1.5 C
F 8 A
G 6 F
H 8 E
R 3.5 D
J 8 G, H
K 6 R
L 4 J, K

The critical chain schedule with buffers added appears below. Project duration is now calculated as 63.5 days.