From this PERT$/$CPM network, answer the following questions.

the arrows by weeks. $[1\mathrm{.}5$ Mark each$]$

Q$7.$ If variance for this project $6,$ what prob. To finish project between $23$ and $33$ weeks

a$.0\mathrm{.}976$

b$.0\mathrm{.}477$

c$.0\mathrm{.}998$

d$.0\mathrm{.}498$

e$.$ none of them