Question

Problem 5-7 The following activities are part of a project to be scheduled using CPM: ACTIVITY IMMEDIATE PREDECESSOR TIME (WEEKS) А 7 B 6 2 3 B.D D b. What is the critical path? Оооо A-C-D-E-G A-B-D-F-G A-B-E-G O A-C-D-F-G c. How many weeks will it take to complete the project? Number of weeks d. How much slack does activity B have? Slack of activity B week(s)

Answer 1

As per the question;

Activity	Immdiate Predecessor	Time (Weeks)
A	-	7
B	A	6
C	A	2
D	C	4
E	B, D	3
F	D	4
G	E,F	6

First we have to schedule the project using CPM ( Critical Path Method). Following is the project network.

E 6 3 A 6 7

b. The critical path is as follows. It is determined by the slack. The Slack is the difference between Latest Start and Earliest Start time or the difference between Latest Finish and Earliest Finish time. If the slack is zero. it makes the critical path.

Earliest Start (ES)	Latest Finish(LF)
Latest Start ( LS)	Earliest Finish(EF)

Slack= 1 Slack= 1 7 13 13 16 ES EF 8 14 14 17 Slack= 0 LS ES 17 23 B. E Slack= 0 17 23 0 7 6 3 7 A 4 6 7 D 13 17 9 13 7 9 13 17 9 13 7 9 Slack= 0 Slack=0 Slack=0 Critical Path is A C D— > F

c. Calculation of the time to complete the project is equal to the duration of critical path. That is,

Project Duration = Duration of activity of A +Duration of activity of C+Duration of activity of D+Duration of activity of F +Duration of activity of G

= 7 + 2 + 4+ 4+ 6

= 23 weeks

d. Slack of activity B = Latest Start - Earliest Start time or Latest Finish - Earliest Finish time

= 8-7 or 14-13

= 1 weeks