The manager of a car wash has received a revised price list from the vendor of the liquid soap, and a promise of a shorter lead time for deliveries. Formerly the lead time was four days, but now the vendor promises a reduction of 25 percent in that time (i.e., new lead time is three days). Annual usage of soap is 4,500 litres. The car wash is open 360 days a year. Assume that daily usage of soap is Normal, and that it has a standard deviation of two litres per day. The ordering cost is $10 per order and annual holding cost rate is 40 percent of unit cost. The revised price list is shown below. LO3 & LO4 Quantity (litres) Unit Price per Litre 1-399 $2.00 400-799 1.80 800+ 1.60 What order quantity is optimal? What ROP is appropriate if the acceptable risk of a stockout is 1.5 percent