A simple CPM network has three activities, D, E, and F. D is an immediate predecessor of E and of F. E is an immediate predecessor of F. The activity durations are D = 5, E = 4, F = 9.
A) The critical path is D-E-F, duration 18.
B) The critical path is D-F, duration 14.
C) Slack at D is 4 units.
D) Slack at E is 4 units.
E) The network has two critical paths.

Question

Quizplus · Accepted Answer

The critical path is the longest path, which in this case is D-E-F with a duration of 18.

Answer: C
 Slack at a particular activity is the amount of time the activity can be delayed without impacting the project duration. Slack at D can be calculated as follows: Slack at D = (EF - D) - (LF - D) = (18 - 5) - (18 - 9) = 4.

Answer: D
 Slack at E can be calculated as follows: Slack at E = (LF - E) - (EF - E) = (18 - 4) - (14 - 4) = 4.

Answer: E
 The network has only one critical path, which is D-E-F. There cannot be two critical paths in a simple CPM network.

A Simple CPM Network Has Three Activities, D, E, and F