5. A centrifugal pump has a mean time between breakdowns of 3,000 hours and a standard deviation of 400 hours (time between failures is Normally distributed). The value of its service (uptime) is $100 per hour. Repair of the pump requires an overhaul. It will cost $1,500 of parts and labour to overhaul the pump. If overhaul is planned, it will cause eight hours of downtime, whereas if it is unplanned, it will cause 24 hours of downtime. What is the optimal scheduled overhaul interval? LO2