help asap please

task time estimates for the modification of an assembly line at Jim Goodale's Carbondale, Illinois, factory are as follows:

$\backslash$table$[[$Activity$,\backslash$table$[[$Time$],[($in hours$)]],$Immediate Predecessor$($s$)],[$A$,6\mathrm{.}0,-],[$B$,6\mathrm{.}7,-],[$C$,6\mathrm{.}0,$A$],[$D$,6\mathrm{.}0,$B$,$ C$],[$E$,5\mathrm{.}1,$B$,$ C$],[$F$,8\mathrm{.}4,$D$],[$G$,4\mathrm{.}0,$E$,$ F$]]$

This exercise contains only part a$.$

a$)$ The correct precedence diagram for the project is shown in$.....$help