The lengths of a particular animal's pregnancies are approximately normally distributed, with mean = 259 days and standard deviation = 12 days. (a) What proportion of pregnancies lasts more than 274 days? (b) What proportion of pregnancies lasts between 241 and 265 days? (c) What is the probability that a randomly selected pregnancy lasts no more than 235 days? (d) A "very preterm" baby is one whose gestation period is less than 229 days. Are very preterm babies unusual? (a) The proportion of pregnancies that last more than 274 days is (Round to four decimal places as needed.)