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minutes. (a) A type of light bulb is labeled as having an average life. time of 1000 hours. It's reasonable to model the prob- ability of failure of these bulbs by an exponential density function with mean u = 1000. Use this model to find the probability that a bulb (i) fails within the first 200 hours, (ii) burns for more than 800 hours. (b) What is the median lifetime of these light bulbs