The estimated times and immediate predecessors for the activities in a project at

Howard Umrah's retinal scanning company are given in the following table. Assume that the

activity times are independent.

This exercise contains only parts $a,b,c,$ and $d.$

a$)$ Based on the activity time estimates, the expected times and variance for each of the

activities are $($round your response to two decimal places$)$:

b$)$ The expected completion time of the project $=$

decimal places$).$

c$)$ The project variance of completion time $=$

places$).$

d$)$ If the time to complete the project is normally distributed, then the probability that the

project will be finished in $21$ weeks or less $=$

response to two decimal places$).$

weeks $($round your response to two

weeks $($round your response to two decimal

$($enter as a probability and round your