The lengths of a particular animal's pregnancies are approximately normally distributed, with mean u = 271 days and standard deviation o = 20 days. (a) What proportion of pregnancies lasts more than 296 days? (b) What proportion of pregnancies lasts between 241 and 276 days? (c) What is the probability that a randomly selected pregnancy lasts no more than 251 days? (d) A "very preterm" baby is one whose gestation period is less than 221 days. Are very preterm babies unusual? (a) The proportion of pregnancies that last more than 296 days is (Round to four decimal places as needed.) (b) The proportion of pregnancies that last between 241 and 276 days is (Round to four decimal places as needed.) (c) The probability that a randomly selected pregnancy lasts no more than 251 days is (Round to four decimal places as needed.) (d) The probability of a "very preterm" baby is . This event unusual because the probability is than 0.05. (Round to four decimal places as needed.)