A large survey found that an American family generates an average of 1 5.1 lb of glass garbage each year. Assuming normal distribution with the standard deviation of 2.3 pounds. (a) What proportion of families generates less than 18 lbs of glass garbage each year? (Round your answer to the nearest hundredth.) (b) If a family is selected at random, what is the probability that it generated less than 18 lbs of glass garbage in a year? (Round your answer to the nearest hundredth.) (c) If a sample of 44 families is randomly selected, what is the probability that the sample mean is below 18 lbs? (Round your answer to the nearest hundredth.) (d) If a sample of 44 families is randomly selected, what is the probability that the sample mean is above 18 lbs? (Round your answer to the three decimal places.)