Final answer:
The typical duration range for a Work Breakdown Structure (WBS) activity is not fixed and can vary, but an average of forty-five days is noted by Willcocks (1913), with various other durations also possible as suggested by Barois (2010).
Step-by-step explanation:
The typical duration range for a Work Breakdown Structure (WBS) activity can vary widely depending on the project's complexity, size, and nature. However, one reference, Willcocks (1913), suggests an average time of forty-five days for a WBS activity. Other durations are given in Barois (2010), suggesting that there can be a range of possible durations for WBS activities, depending on various project factors.