$\backslash$table$[[$Activity $($from WBS$),$Activity No$.,$Predecessors,$\backslash$table$[[$Duration$],[($days$)]]],[$Decide on colour to paint room,A$,-,0,5],[$Prepare walls and ceiling,B$,$A$,$ E$,1],[\backslash$table$[[$Buy paint and materials for$],[$preparation of walls & ceiling$]],$E$,$A$,0,5],[$Paint ceiling,C$,$B$,$ A$,$ E$,1],[$Paint walls,D$,$B$,$ A$,$ E$,1],[$Order new curtains,F$,$A$,0,5]]$

a$)$ Draw a network for the data given in the Table above

b$)$ What arrows would be correct but unnecessary?