PMI-SP Exam - Topic 9 Question 41 Discussion

A three-point estimate records the optimistic, most likely, and the pessimistic duration

and then records an average for the predicted duration.

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.

Here it is,

TE = ( 24 + 28*4 + 36) / 6

= 272/6

= 29 (approx)

Answer options B, D, and A are incorrect. These are not the valid answers for this question.