A project consists of four consecutive tasks that have average duration and worst-case duration estimates (in days)as shown in the table.Use Newbold's model to determine the aggregated one sigma buffer for this project. $$\begin{array} { | l | l | l | }
\hline\text { Activity } & \text { Average } & \text { Worst-Case } \
\hline \mathrm { A } & 10 & 20 \
\hline \mathrm {B }& 15 & 25 \
\hline \mathrm { C } & 20 & 30 \
\hline \mathrm { D } & 25 & 35 \
\hline
\end{array}$$
A)20 days
B)10 days
C)15 days
D)5 days

Question

A project consists of four consecutive tasks that have average duration and worst-case duration estimates (in days)as shown in the table.Use Newbold's model to determine the aggregated one sigma buffer for this project. $$\begin{array} { | l | l | l | } 
\hline\text { Activity } & \text { Average } & \text { Worst-Case } \
\hline \mathrm { A } & 10 & 20 \
\hline  \mathrm {B }& 15 & 25 \ 
\hline \mathrm { C } & 20 & 30 \
\hline \mathrm { D } & 25 & 35 \
\hline
\end{array}$$ 
A)20 days
B)10 days
C)15 days
D)5 days

Quizplus · Accepted Answer

Using Newbold's model, the aggregated one sigma buffer can be calculated as:
Square root of [(3*(6^2 + 9^2 + 4^2)) - ((6+9+4)^2)]
= Square root of [(3*(36 + 81 + 16)) - (361)]
= Square root of [(387) - (361)]
= Square root of 26
= 5.099

Rounding this up to the nearest whole number gives a one sigma buffer of 5 days. Therefore, the best choice is D).

A Project Consists of Four Consecutive Tasks That Have Average