How to find average stock level
Average inventory is a calculation that estimates the value or number of a particular good or set of goods during two or more specified time periods. Average inventory is the mean value of an inventory within a certain time period, which may vary from the median value of the same data set, A Z-score of 1.65, satisfying demand with a 95% confidence level, is generally regarded as acceptable even for important stock. In this case, that would mean stocking approximately 18 units (the standard deviation of 11 x 1.65) of safety stock, or 38 units total (average demand + safety stock).