OCR MEI D1 2011 January — Question 4

Exam BoardOCR MEI
ModuleD1 (Decision Mathematics 1)
Year2011
SessionJanuary
TopicCritical Path Analysis

4 The table shows the tasks involved in preparing breakfast, and their durations.
TaskDescriptionDuration (mins)
AFill kettle and switch on0.5
BBoil kettle1.5
CCut bread and put in toaster0.5
DToast bread2
EPut eggs in pan of water and light gas1
FBoil eggs5
GPut tablecloth, cutlery and crockery on table2.5
HMake tea and put on table0.5
ICollect toast and put on table0.5
JPut eggs in cups and put on table1
  1. Show the immediate predecessors for each of these tasks.
  2. Draw an activity on arc network modelling your precedences.
  3. Perform a forward pass and a backward pass to find the early time and the late time for each event.
  4. Give the critical activities, the project duration, and the total float for each activity.
  5. Given that only one person is available to do these tasks, and noting that tasks B, D and F do not require that person's attention, produce a cascade chart showing how breakfast can be prepared in the least possible time.