If the maximum duration of an activity is $10$ and the minimum duration is $4,$ what is the variance for the activity time when using CPM analysis?

Group of answer choices

$1\mathrm{.}33$

$1\mathrm{.}00$

$2\mathrm{.}33$

$5\mathrm{.}00$

$8\mathrm{.}00$