The Bank of Johnstown is planning to install a new accounts system. Bank management has determined the activities required to complete the project, the precedence relationships of the activities, and activity time estimates in the following table. Determine $($a$)$ ?the earliest and latest activity times, $($b$)$ ?the expected completion time and standard deviation, and $($c$)$ ?the probability the project will be completed in $40$ ?weeks or less.