PERT is use full when we have following time duration except:a.Optimistic timeb.Pessimistic timec.Most likely timed.Certain Duration

The PERT (Program Evaluation and Review Technique) is a statistical tool used in project management, which is designed to analyze and represent the tasks involved in completing a given project. It incorporates uncertainty by making it possible to schedule a project while not knowing precisely the details and durations of all the activities.

The time estimates in PERT include:

a. Optimistic time: the minimum possible time required to accomplish a task, assuming everything proceeds better than is normally expected.

b. Pessimistic time: the maximum possible time required to accomplish a task, assuming everything goes wrong (but excluding major catastrophes).

c. Most likely time: the best estimate of the time required to accomplish a task, assuming everything proceeds as normal.

The option that PERT does not use is:

d. Certain Duration: PERT is designed to handle uncertainty in activity completion times. Therefore, it does not use a certain duration as it assumes there is always some degree of uncertainty in how long each task will take.