Activity networks and precedence tablesEdexcel International A Level Maths: Mind map

Exam questions on Activity networks and precedence tables

1. A project has five activities, A to E. Activities A and B have no predecessors. C has immediate predecessor A only. D has immediate predecessors A and B. E has immediate predecessors C and D. The project is modelled by an activity network with activities on arcs.
   Explain why the correct network needs a dummy activity, and state where the dummy is drawn.2 marks
2. A project has six activities, P to U. P and Q have no predecessors. R has immediate predecessor P only. S has immediate predecessors P and Q. T has immediate predecessor Q only. U has immediate predecessors R, S and T. The project is modelled by an activity-on-arc network.
   Explain why S needs dummy activities but R and T do not.2 marks
3. An activity network has start event 1 and finish event 6. Its arcs are: A from event 1 to event 2; B from 1 to 3; C from 2 to 4; a dummy from 2 to 3; D from 3 to 4; E from 3 to 5; F from 4 to 6; G from 5 to 6.
   Write down the immediate predecessors of each of the activities A, B, C, D, E, F and G.3 marks