Question $4$

Durations for a project's four key activities are shown. What is the mean duration of Activity $1$ using the Project Evaluation and Review Technique $($PERT$)$ Handook p$428?$

Here is the link to the Handbook and it should open in a new tab

$9\mathrm{.}5$

$10$

$6$

$7\mathrm{.}5$