Question

Based upon the following tasks, durations and predecessor relationships which of the following tasks is not critical? 1, 10, N/A; 2,8,1; 3,5, 1; 4, 9, 1; 5, 6, 3; 6, 6, 2; 7, 11, 5; 8, 10, 6; 9, 9, 4; 10, 7, 9; 11, 10,( 7,8,10);

a. 4

b. 9

c. 6

d. 10

Answer 1

Drawing a relationship diagram of the activities we see that activity 1 is the start and activity 11 is the end activity. And there are 3 paths between the start and end. The longest path among the three paths will be critical.

Path (i) - 2-6-8 = 8days + 6days + 10days = 24days

Path (ii) - 3-5-7 = 5days + 6days + 11days = 22days

Path (iii) - 4-9-10 = 9days + 9days + 7days = 25days (longest of the three paths and critical)

Therefore critical activities are 1-4-9-10-11.

Hence 6 is the only non-critical activity, among the options.

ANS: c. 6

Alternatively, network analysis can be done to find the required non-critical activity.

6 is a non- critical activity.

ANS: c. 6