The injection moulding department of a company uses an average of 30 gallons of special lubricant a day. The supply of the lubricant is replenished when the amount on hand is 170 gallons. It takes four days for an order to be delivered. Safety stock is 65 gallons, which provides a stock out risk of 9 percent. What amount of safety stock would provide a stock out risk of 3 percent? Assume normality.