Activity 7-8 is directly preceded by two activities-activity 5-7 and activity 6-7. Activity 5-7 has an expected time of five and an ES time of six. Activity 6-7 has an expected time of seven and an ES time of seven. Activity 7-8 has an expected time of 10. The ES for activity 7-8 is
A)11.
B)14.
C)21.
D)24.
E)25.

Question

Quizplus · Accepted Answer

The Earliest Start (ES) time for activity 7-8 is calculated by adding the longest path leading to it. The ES times for activities 5-7 and 6-7 are 6 and 7, respectively. Adding the expected times to these gives 11 (6+5) for activity 5-7 and 14 (7+7) for activity 6-7. Since activity 7-8 can only start after both preceding activities are finished, and we choose the longest path to determine the ES for activity 7-8, the correct ES time for activity 7-8 is 14, the end of the longest preceding activity.

Activity 7-8 Is Directly Preceded by Two Activities-Activity 5-7 and Activity