JC Manufacturing has fifty 100-horsepower motors at their plant. Each motor is rated for 10,000 hours. There were six failures prior to reaching 10,000 hours. The failures occurred at 800, 4000, 6500, 500, 800, and 400 hours respectively. forty-four motors were still operating at the end of 10,000 hours. The motors that failed were not replaced. Determine the mean life