The operational life of a particular LED bulb is normally distributed with a mean of W300 hours and a standard deviation of 600 hours. A. What is the probability that a randomly selected LED bulb will reach the end of its useful life before 5300 hours? {2 points) B. What should the mean operational life equal for 99% of randomly selected LED bulbs to exceed 7'000 hours before failure? Assume that the standard deviation stays same at 600 hours. {2 points) C. If a factory has 20 LED bulbs installed and they are assumed to fail independently, what is the probability that at least 5 of the 20 LED bulbs are still operating after ?000 hours? (2 points)