Text book states A) 130hr, B) 256 hr, C) 155 hr, D) 513 hr

2. The failure rate for a high-speed fan is given by 2(t) = (2 x 10# + 3 x 10%t) / hr, Where t is in hours of operation. The required design-life reliability is 0.95. How many hours of operation should the design life be? If, by preventive maintenance, the wear contribution to the failure rate can be eliminated, to how many hours can the design life be extended? By placing the fan in a controlled environment, we can reduce the contribution of random failure to 2(t) by a factor of two. Then, without preventive maintenance, to how many hours may the design life be extended? What is the extended design life with both preventive maintenance and controlled environment