An insurance application consists of two forms, F1 and F2. Upon receipt, each application is processed, recorded and separated into F1 and F2. This operation is done by a data-entry clerk and requires 6 minutes. F1 is processed by professional A for 20 minutes per unit and then by professional B for 10 minutes per unit. Professional C processes F2 for 20 minutes per unit. F1 and F2 are then combined and further processed by a loan officer for 15 minutes. The staffing of the process utilizes one each of professionals A, B, and C, one data entry clerk, and one loan officer.

Facing the coming busy season, two new staffs E and F are recently hired. Both of them can do data entry in 10 min, screening F1 in 30 min, rating F1 in 20 min, rating F2 in 20 min. Each of them will be asked to perform a single task.

Required: which positions should E and F be asked to take, respectively?