Question

Mary reports that, on a productive week, she can develop the system requirements in four days, but during a normal week it should take around eight days. during the time frame that mary will be working on the requirements, things will be very hectic and this could cause the requirements to take as much as twelve days. what is the expected duration for gathering system requirements using three-point method

Answer 1

Answer: The expected duration for gathering system requirements using three-point method is 8 days.

We obtain the same answer when we use the Simple Average method and the PERT method.

We follow these steps while arriving at the answer.

We have the following information from the question:  

Optimistic Value (O) -  4 days (best estimate of time taken to complete the task)

Most Likely Value (M) – 8 days (realistic estimate of time taken to complete the task)

Pessimistic Value (P) – 12 days (worst estimate of time taken to complete the task)

There are two formulas we can use to determine the expected duration by using the three-point estimation method.

1. Simple Average method: We use the following formula under this method.

         $E_{SA} = \frac{O+P+M}{3}$

         $E_{SA} = \frac{4+12+8}{3}$

         $E_{SA}  = 8 days  (\frac{24}{3} )$

       2. PERT method. The formula for this is:

          $E_{PERT} = \frac{O+P+4M}{6}$  

          $E_{PERT} = \frac{4+12+(4*8)}{6}$  

          $E_{PERT} = \frac{48}{6}$

           $E{PERT} = 8 days$