Question

In a project activity for completion, if the most optimistic time is 4 days, most likely time is 6 days & most pessimistic time is 11 days, then the Expected time shall be:
1. 5.5 days 
2. 6.5 days
3. 8 days
4. 7 days

Answer 1

Correct Answer - Option 2 : 6.5 days

Concept:

The PERT (Project Evaluation and Review Technique) technique is used, when activity time estimates are stochastic in nature. For each activity, three values of time (optimistic, most likely, pessimistic) are estimated.

• Optimistic time (to) estimate is the shortest possible time required for the completion of an activity
• Most likely time (tm) estimate is the time required for the completion of activity under normal circumstances
• Pessimistic time (tp) estimate is the longest possible time required for the completion of an activity

In PERT expected time of an activity is determined by using the below-given formula:

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

Calculation:

 Given,

 optimistic time (t_o) = 4 days, most likely time (t_m) = 6 days

 pessimistic time (t_p) = 11 days

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

  \(t_e = \frac{{4\ +\ \left( 4\times{{6}} \right) +\ 11}}{6}\)

   te = 6.5 days