Demand for walnut fudge ice cream at the Sweet Cream Dairy can be approximated by a normal distribution with a mean of 21 gallons per week and a standard deviation of 10 gallons per week. The new manager desires a service level of 90 percent. Lead time is 9 days, and the dairy is open seven days a week. (Hint: Work in terms of weeks.) If the ROP model is used, what is the appropriate safety stock level to achieve the desired service level? Round to two decimal places