Question

A company manufactures fuses which may have a service life approached by a normal distribution having an average of 1000 hours and a standard deviation of 200 hours. 1. What is the probability that a fuse will work for more than 1330 hours? 2. The company would like to offer a replacement guarantee for everything fuse with an operating time not exceeding x0 hours. Determine x0 if the company intends to replace a maximum of 2.5% of its fuses with this guarantee. 3. A sample of 10 fuses is taken at random and put into service in a process where they operate independently of each other. Calculate the probability that at least 8 of the fuses in the sample will not work more after 1330 hours?

Answer 1