Stock level based on historical demand and supply

[StevieV]

I have historical data for each month since Jan 2005 showing # stock going out of a location(demand) and stock coming in (supply). Both are pretty random. Is there a formula I can use that can tell me how much stock I need to have in order to fullfill 95% of demand based on this historic data? I have calculated the Mean, Min, Max and SD of both but have no idea how to combine this info.

Thanks!
Steve

 

[stapel]

I'm sorry, but I'm not clear on what you're asking. Please reply with the exact text of and instructions for this exercise. Please also include the definition of "demand" for this context. Thank you.

Eliz.