Cost Driver Analysis - Need formula to allocate manpower cost

I am working on calculating the cost drivers.

We have 19 “Departments”, 11 “Head of the Departments” and around 1000+ “Employees”.

Due to Job rotation, Supervisory, Internal Expertise etc staff are often pulled / allocated to other department out of their parent department.

Form the staff attendance software we could get the monthly data of each staff worked in which department.

I have attached a sample database and my requirements.

I would appreciate if someone could help me getting the formula in the highlighted range of the attached worksheet.

Regards

Swastik