Question

In a pert activity, optimistic time is 5 hr, pessimistic time is 20 hr and the most likely time is 10 hr then what is the expected time for completion of the activity (in hours)?

1. 11.13
2. 10.833
3. 9
4. 10

Answer 1

Correct Answer - Option 2 : 10.833

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:

t_o = 4 hr, t_m = 10 hr, and t_p = 20 hr

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

\({t_e} = \frac{{ {{5} \;+ \;4{(10)} \;+ \;{20}} }}{6}\Rightarrow 10.833\;hr\)