An activity on a PERT network has these time estimates: optimistic $=2,$ most likely $=3,$ and pessimistic $=8.$ Its expected time and variance $($ff it is a critical activity$)$ are

Select the correct response:

none of these

$4\mathrm{.}33$;$6$

$4\mathrm{.}33$;$1$

$3\mathrm{.}67$:$6$

$3\mathrm{.}67$;$1$