Answer:
Checking the flow per staff:
data entry clerk = 8 mins/application = 60/8 = 7.5 applications per hour
Staff A = 20 mins = 60/20 = 3 F1 screening/hour
Staff B = 10 mins = 60/10 = 6 F1 rating/hour
Staff C = 15 mins = 60/15 = 4 F2 rating/hour
2 loan officers = 15 mins = 60/15 = 4 (but 2 officers) = 8 applications/hour
the minimum flow comes in Staff A, F1 screening with just 3 /hour, and next minimum is at Staff C at 4/hour
one new staff E is put for Screening F1 = 30 mins = 2 applications/hour, this would increase the flow to 5 applications/hour
after this the bottle neck is at F2 rating, hence F is placed at F2 rating with staff C = 20 mins = 3 applications /hour
increasing the flow to 4+3 = 7 applications/hour.