$1.$ Assume the time used for each activity is the expected time required to finish that activity, and the project completion time calculated in part $4$ is the expected completion time for the project and also project variance is $10$ weeks. What is the probability of finishing the project within a range of $3$ weeks earlier than the expected completion time and $1$ week later? Additionally, what is the probability of finishing the project $4$ or more weeks beyond the expected completion time? Lastly, what due date would yield a $75\%$ chance of completion?