A Project Consists of Four Activities with Information as Shown

Multiple Choice

A project consists of four activities with information as shown in the table.What is the overall standard deviation of the project? $$\begin{array} { | l | l | l | l | } \hline \text { Activity } & \text { Predecessor } & \text { Length } & \text { Variance } \\\hline \mathrm { A } & - - & 10 & 4 \\\hline\mathrm { B} & \mathrm {A } & 12 & 3 \\\hline \mathrm {C } & \mathrm { B } & 16 & 5 \\\hline \mathrm { D } & \mathrm { C } & 14 & 6 \\\hline\end{array}$$

A) 24
B) 18
C) 8.41
D) 4.24