Does it take an expert to figure out that simple math problem??
The fact you assume the simple formula of total # of employees (effort) to produce total # of items (phones) as the metric for efficiency shows how inexperience and unqualified you are to for anything related to the manufacturing at this scale. There are so many internal and external factors with various vendors and supplies all working together but hey... you come in and BAMM 2.7/person sucks!. I am an expect to this simple problem.
Why don't you go work for Apple? With your internet wisdom I'm sure you can solve anything.. No more pre-orders or delays for any products in the world thanks to you.