2. Let x be a random variable that represents the delivery time (in hours) for packages delivered by a company. You may assume that x is normally distributed with mean u = 14 and standard deviation a = 2.3. a. For a package selected at random, what is the probability that it will be delivered in at most 18 hours? D. For a random sample of 20 packages, what is the probability that the sample mean delivery time is at least 13.5 hours