Hi
i am trying to calcualte the efficieny of a team

a1 = mins_available ( 60)
b1 = target (100)
c1 = stoppages (in minutes)
d1 = achieved (ie 50)

i have this formula
(target*(mins_available-stoppages)/mins_available)/target

problem is this does not take into account the quantity achieved
against the target

what i am trying to do is find out how long they actually worked
take what they actually achieved and work out how efficient they were
in the available time against the target

can anyone help please

kevin