The life of a semiconductor laser at a constant power is normally distributed with a mean of 7000 hours and a standard deviation of 600 hours. a. What is the probability that a laser fails before 500 hours? b. What is the life in hours that 95% of the lasers exceed? c. If three lasers are used in a product and they are assumed to fail independently, what is the probability that all three are still operating after 7000 hours?
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