Katty needs to purchase milk to make ice cream. The supplier charges a $60 fixed fee per order and $4.75 per kg. Her annual holding cost is 25%. She needs 1000 kgs of milk per day. Assume 52 weeks per year and 5 days per week. If Katty wants to minimize inventory holding and ordering costs, about how long the milk is kept in her store on average? (i.e. Average Flow Time)