ESSAY. Write your answer in the space provided or on a separate sheet of paper. $1)$ A network consists of the activities in the following list. Times are given in weeks. PrecedingTimeA$--7$B$--15$CA$3$DA$,$ B$9$EC$12$FD$6$ a$.$ Draw the network diagram. $(5$ points$)$b$.$ Calculate the ES$,$ EF $,$LS$,$ LF $(10$ points$)$c$.$ Calculate the amount of Slack $(5)$ pointsd. What is project completion time? $(5$ points$)$e$.$ If activity C was delayed by $3$ time units, what would happen to the project duration $(5$ points$)$