4. (a) Draw the activity network described by the precedence table below, using activity on arc. Use dummies only where necessary.
(5)
| Activity | Immediately preceding activities |
| A | - |
| B | - |
| C | A |
| D | A, B |
| E | C, D |
| F | D |
| G | C |
| H | G |
| I | G |
| J | E, F, I |
| K | F |
Given that K is a critical activity,
(b) state which other activities must also be critical.
(1)
Given instead that all activities shown in the precedence table have the same duration and K is not necessarily critical,
(c) state the critical path for the network.
(1)