A small software development project has five major activities. The times are estimated and provided in the table below.

Activity Immediate

Predecessor a m b

A $--258$

B $--101010$

C A $4710$

D B $2514$

E C $333$

$($a$)$ Draw the network

$($b$)$ What is the expected completion time for this project?

$($c$)$ What variance would be used in finding probabilities of finishing by a certain time?