create a CPM DIAGRAM

\begin{tabular}{|c|c|c|c|c|c|l} \hline Activity & Activity Desc. & Optimistic & Most likely & Pessimistic & \begin{tabular}{c} Immediate \\ Predecessors \end{tabular} & Expected Time \\ \hline A & Excavate & 1 & 2 & 3 & - & \\ \hline B & Lay the foundation & 2 & 3.5 & 8 & A & \\ \hline C & \begin{tabular}{c} Put up the rough \\ wall \end{tabular} & 6 & 9 & 18 & B & \\ \hline D & Put up the roof & 4 & 5.5 & 10 & C & \\ \hline E & \begin{tabular}{c} Install the exterior \\ plumbing \end{tabular} & 1 & 4.5 & 5 & C & \\ \hline F & \begin{tabular}{c} Install the interior \\ plumbing \end{tabular} & 4 & 4 & 10 & E & \\ \hline G & \begin{tabular}{c} Put up the exterior \\ siding \end{tabular} & 5 & 6.5 & 11 & D & \\ \hline H & \begin{tabular}{c} Do the exterior \\ painting \end{tabular} & 5 & 8 & 17 & E, G & \\ \hline I & \begin{tabular}{c} Do the electrical \\ work \end{tabular} & 3 & 7.5 & 9 & C & \\ \hline J & Put up the wallboard & 3 & 9 & 9 & F, I & \\ \hline K & Install the flooring & 4 & 4 & 4 & J & \\ \hline L & \begin{tabular}{c} Do the interior \\ painting \end{tabular} & 1 & 5.5 & 7 & J & \\ \hline M & \begin{tabular}{c} Install the exterior \\ fixtures \end{tabular} & 1 & 2 & 3 & H & \\ \hline N & \begin{tabular}{c} Install the interior \\ fixtures \end{tabular} & 5 & 5.5 & 9 & K, L & \\ \hline \end{tabular}