We also have some supplies where we need to keep safety stock and need to know when we should best reorder - there is variability in both the time it takes to receive the supplies and variability in our demand (both fluctuate in a normally distributed way). We don't want more than a 1% chance of running out-of-stock while replenishing.

What info would we need to give you to tell us what our safety stock should be, and at what stock level we should reorder?