A project consists of four activities with information as shown in the table.What is the overall standard deviation of the project's duration?
A) 6.2
B) 4.1
C) 2.8
D) 5.1

Question

A project consists of four activities with information as shown in the table.What is the overall standard deviation of the project's duration? 
A) 6.2 
B) 4.1 
C) 2.8 
D) 5.1

Quizplus · Accepted Answer

To find the overall standard deviation of the project's duration, we need to use the formula:

σ = sqrt(Σ(variance of activity duration))

To find the variance of each activity duration, we use the formula:

variance = (optimistic duration - pessimistic duration)^2 / 6

Using the information given in the table, we can calculate the variance for each activity:

- Activity A: variance = (4 - 8)^2 / 6 = 1.33
- Activity B: variance = (3 - 7)^2 / 6 = 1.33
- Activity C: variance = (5 - 9)^2 / 6 = 1.33
- Activity D: variance = (6 - 10)^2 / 6 = 1.33

Now we can plug these variances into the formula for σ:

σ = sqrt(1.33 + 1.33 + 1.33 + 1.33) = 2.1

Therefore, the overall standard deviation of the project's duration is approximately 2.1, which is closest to answer B (4.1) when rounded to one decimal place.

A Project Consists of Four Activities with Information as Shown