The Central Limit Theorem states: Let 1,…, be a random sample with []= and ()=2 . If is sufficiently large, then ¯ has approximately a normal distribution with mean ¯= and variance 2¯=2/ . It's also true that ∑=1∼(,2) . Suppose a machine requires a specific type of battery that lasts an exponential amount of time with mean 25 hours. As soon as the battery fails, you replace it immediately. If you have 50 such batteries, estimate the probability that the machine is still operating after 1300 hours