10 valet parkers (guys to park guest cars in parking) park 90 cars daily (24 Hours) and takes out 60 cars daily (in 24 Hours). How can i calculate their productivity. I want to assess that either i need really 10 valet parkers for this turn over of cars or i need either to reduce the staff or i need to increase the staff. I need and excel formula to see their productivity within 24 Hrs. with this turn out of cars. Thanks to help please.