Use the Values in the Table to Calculate Activity Durations

Use the values in the table to calculate activity durations and variances for the project.What is the likelihood that the project takes between 60 and 55 days to complete?
$\begin{array}{|l|l|l|l|}\hline \text { Activity } & \text { Activity time } & \begin{array}{l}\text { Standard } \\\text { deviation }\end{array} & \text { Predecessor } \\\hline \mathrm{A} & 12 & 3 & \\\hline \mathrm{B} & 8 & 2 & \mathrm{~A} \\\hline \mathrm{C} & 9 & 1 & \mathrm{~A} \\\hline \mathrm{D} & 5 & 1 & \mathrm{~B} \\\hline \mathrm{E} & 12 & 0 & \mathrm{~B} \\\hline \mathrm{F} & 10 & 0 & \mathrm{C} \\\hline \mathrm{G} & 7 & 2 & \mathrm{C} \\\hline \mathrm{H} & 9 & 3 & \mathrm{E}, \mathrm{G} \\\hline \mathrm{I} & 15 & 2 & \mathrm{D}, \mathrm{G} \\\hline \mathrm{T} & 8 & 2 & \mathrm{H} \\\hline \mathrm{K} & 11 & 3 & \mathrm{I} \\\hline \mathrm{L} & 7 & 2 & \mathrm{~J}, \mathrm{~K} \\\hline\end{array}$