Question

For an activity the pessimistic, most likely and optimistic time are 10 days, 6 days and 2 days respectively. The expected duration of activity based on Beta distribution will be:
1. 6 days
2. 3 days
3. 2 days
4. 9 days

Answer 1

Correct Answer - Option 1 : 6 days

Concept:

Project Evaluation and Review Technique (PERT) is probabilistic in nature and is based upon three-time estimates to complete an activity.

Optimistic Time (to): It is the minimum time that will be taken to complete an activity if everything goes according to the plan.

Pessimistic Time (tp): It is the maximum time that will be taken to complete an activity when everything goes against the plan.

Most likely time (tm): It is the time required to complete a project when an activity is executed under normal conditions.

Average or most expected time is given by \({t_E} = \left( {\frac{{{t_p}\; + \;4{t_m}\; + {t_o}}}{6}} \right)\)

Calculation:

Given:

Pessimistic Time (t_p) = 10 days, Most likely time (t_m) = 6 days, Optimistic Time (t_o) = 2 days

Average or most expected time is given by 

\({t_E} = \left( {\frac{{{t_p}\; + \;4{t_m}\; + {t_o}}}{6}} \right)\)

\({t_E} = \left( {\frac{{{10}\; + \;4\times{6}\; + {2}}}{6}} \right)=6\;days\)