$3.$ A project is comprised of five tasks. The precedence relationships and crash information are given in the following table.

$($c$)$ The current project completion time

$($d$)$ The current total slack time for non$-$critical paths $=$ days and the total slack time for non$-$critical activities $\backslash (=\backslash )$ days.

$($e$)$ If you need to shorten the project completion time by one day, you should crash activity first and spend thousand dollars at least.

$($f$)$ If you need to shorten the project completion time by four days in total, the total minimum crash cost $\backslash (=\backslash )$

$($g$)$ What is the minimal time required to complete the project and how much does it cost$?$