4 Answer this question on the insert provided.
The table shows activities involved in a "perm" in a hair salon, their durations and immediate predecessors.
\begin{table}[h]
| Activity | Duration (mins) | Immediate predecessor(s) |
| A | shampoo | 5 | - |
| B | prepare perm lotion | 2 | - |
| C | make coffee for customer | 3 | - |
| D | trim | 5 | A |
| E | clean sink | 3 | A |
| F | put rollers in | 15 | D |
| G | clean implements | 3 | D |
| H | apply perm lotion | 5 | B, F |
| I | leave to set | 20 | C,H |
| J | clean lotion pot and spreaders | 3 | H |
| K | neutralise and rinse | 10 | I, E |
| L | dry | 10 | K |
| M | wash up and clean up | 15 | K |
| N | style | 4 | G, L |
\captionsetup{labelformat=empty}
\caption{Table 4}
\end{table}
- Complete the activity-on-arc network in the insert to represent the precedences.
- Perform a forward pass and a backward pass to find early and late event times. Give the critical activities and the time needed to complete the perm.
- Give the total float time for the activity \(G\).
Activities \(\mathrm { D } , \mathrm { F } , \mathrm { H } , \mathrm { K }\) and N require a stylist.
Activities \(\mathrm { A } , \mathrm { B } , \mathrm { C } , \mathrm { E } , \mathrm { G } , \mathrm { J }\) and M are done by a trainee.
Activities \(I\) and \(L\) require no-one in attendance.
A stylist and a trainee are to give a perm to a customer. - Use the chart in the insert to show a schedule for the activities, assuming that all activities are started as early as possible.
- Which activity would be better started at its latest start time?