An activity on a probablistic time network diagram has these time estimates: optimistic $=2,$ most likely $=3,$ and pessimistic $=10.$ What is its expected activity time and variance?

Expected time: $4$

Variance: $1\mathrm{.}78$

Expected time: $5$

Variance: $1\mathrm{.}33$

Expected time: $4$

Variance: $10\mathrm{.}67$

Expected time: $5$

Variance: $1\mathrm{.}78$

Expected time: $5$

Variance: $10\mathrm{.}67$