The demand for frozen yogurt at the fictional Garland Ice Cream and Dairy store can be approximated by a normal distribution with a mean of 50 gallons per day and a standard deviation of 6 gallons per day. The lead time from the supplier is a constant 4 days. If the store replenishes its supply of frozen yogurt when the inventory level drops to 220 gallons, what is the safety stock, and how much protection against stock-outs does it provide?