Critical Activities & Critical Paths (AQA Level 3 Mathematical Studies (Core Maths)): Revision Note

Critical Activities & Critical Paths

What is a critical activity?

• In a project, some activities may be critical

  • Any delay to a critical activity will delay the entire project

• Other activities in a project are not critical

  • There is some slack in the timing of a non-critical activity, it can be delayed without without delaying the entire project

• Any slack time available is described by the float of an activity

  • float = latest finish time - earliest start time - duration of activity

• If the float of an activity is equal to 0, it is a critical activity

• If the float of an activity is greater than 0, it is not a critical activity

  • The float of an non-critical activity is the length of time it can be delayed for without delaying the entire project

What is a critical path?

• A path through a network consisting only of critical activities is known as a critical path

  • Each activity on the critical path has a float of 0

  • The length of the critical path is the minimum duration of the entire project

  • E.g. In the diagram below the critical path, A-D-F-G, is highlighted