I am sure that this is a simple problem for many but I am having trouble finding a solution for this:
I have the sales history of a certain specific product-A being sold from a supermarket store. Specifically, I have the data on:
1) the maximum number of units of product-A on the shelves everyday (at the start of the day)
2) the minimum number of units of product-A remaining on the shelves on that day (after certain units are sold/damaged/broken at the end of the day)
I have the above data for over a period of 90 days.
Given this data and the fact that the sales of product-A aren't affected significantly in any holiday season, what is the number of units of product-A I should hold on the shelves at the beginning of the day, with a 90% certainty that it doesn't drop to zero at the end of the day?
Any help will be greatly appreciated. Thank you!