Consider the following project network.

$($i$)$

Suppose that the following estimates of activity times $($in weeks$)$ were provided for the network shown above.

$\backslash$table$[[$Activity$,$Optimistic,Most Probable,Pessimistic$],[$A$,4\mathrm{.}0,5\mathrm{.}0,6\mathrm{.}0],[$B$,2\mathrm{.}5,3\mathrm{.}0,3\mathrm{.}5],[$C$,6\mathrm{.}0,7\mathrm{.}0,8\mathrm{.}0],[$D$,5\mathrm{.}0,5\mathrm{.}5,9\mathrm{.}0],[$E$,5\mathrm{.}0,7\mathrm{.}0,9\mathrm{.}0],[$F$,2\mathrm{.}0,3\mathrm{.}0,4\mathrm{.}0],[$G$,8\mathrm{.}0,10\mathrm{.}0,12\mathrm{.}0],[$H$,6\mathrm{.}0,7\mathrm{.}0,14\mathrm{.}0]]$

$($a$)$ Within $20$ weeks?

$($b$)$ Within $22$ weeks?

$($c$)$ Within $23$ weeks?