A PERT$/$CPM activity has an optimistic time estimate of $3$ days, a most likely time estimate of $8$ days, and a pessimistic time estimate of $10$ days. The expected time $($in days$)$ of this activity is

$7\mathrm{.}0$

$7\mathrm{.}5$

$8\mathrm{.}0$

$8\mathrm{.}5$

$10\mathrm{.}0$

None of the above