Page 15 - OPERATIONS RESEARCH

It is apparent from that the critical path comprises the tasks (1,3), (3,4), (4,6), (6,7). This path
represents the shortest time to complete the entire project.

PROBABILITY CONSIDERATION IN PERT

Under the conditions of uncertainty, the estimated time for each activity for PERT network is

represented by a probability distribution. This probability distribution of activity time is based
upon three different time estimates made for each activity. These are as follows

=the optimistic time, is the shortest possible time to complete the activity if all goes well,

= the pessimistic time, is the longest time that an activity could take if everything goes wrong,

= the most likely time, is the estimate of the normal time an activity would take. If only one

time were available, this would be it. Otherwise it is the mode of the probability distribution.
The range specified by the optimistic

time ( ) and pessimistic time ( ) estimates

supposedly must enclose every possible
estimate of the duration of the activity. The

most likely time ( ) estimate may not

coincide with the midpoint ( + )/2 and

may occur to its left or to its right as given,