You are the project manager for the GRT Project in your organization. You have created your time
duration estimates based on historical information, but the estimates are not holding true in your
current project. Unfortunately, many activities are late. You have decided to create a PERT
estimate with your project team for each of their activities. What is the formula used for PERT?

A.
O+M+P

B.
(O+M+P)/3

C.
(O+4M+P)/6

D.
Average of the estimates

Explanation:
PERT uses the formula of (O+4M+P)/6 to predict the duration of the project activities and the
overall project schedule. Three-point estimate is a way to enhance the accuracy of activity
duration estimates. This concept is originated with the Program Evaluation and Review Technique
(PERT). PERT charts the following three estimates: Most likely (TM): The duration of activity
based on realistic factors such as resources assigned, interruptions, etc. Optimistic (TO): The
activity duration based on the best-case scenario Pessimistic (TP): The activity duration based on
the worst-case scenario The expected (TE) activity duration is a weighted average of these three
estimates: TE = (TO + 4TM + TP) / 6 Duration estimates based on the above equations
(sometimes simple average of the three estimates is also used) provide more accuracy.
Answer option A is incorrect. This is not a valid formula.
Answer option D is incorrect. This almost describes the three-point estimate, but does not answer

the question about PERT.
Answer option B is incorrect. This is the formula for the three-point estimate. Note the PERT, while
similar, uses 4M and divides the result by six factors.