Two pumps can be used for pumping a corrosive liquid. a pump with a brass impeller costs $800 and is expected to last 3 years. a pump with a stainless steel impeller costs $1900 and will last 5 years. a rebuild costing $300 will be required after 2000 operating hours for the brass impeller pump while an overhaul costing $700 will be required for the stainless steel pump after 8000 hours. if the operating cost of each pump is $1 per hour, how many hours per year must the pump be required to justify the purchase of the more expensive pump? use an interest rate of 10% per year.