Q2. 0 The lifetime of a certain brand of lightbulb can be approximated by an exponential distribution. 0 The manufacturer claims the average lifetime is 10,000 hours. (a) Calculate the probability that a randomly chosen lightbulb lasts for more than 20,000 hours? (b) What is the probability that a randomly chosen lightbulb lasts for more than 8,000 hours? (0) Given that a lightbulb has survived for 8,000 hour already, what is the probability it will survive past 20,000 hours