The length of human pregnancies from conception to birth varies according to a distribution that is approximately normal with mean 264 days and standard deviation 16 days. Round all answers to the nearest whole numnber. What is the probability that a pregnancy last less than 260 days? What is the probability that a pregnancy last between 250 and 280 days? Doctors agree that serious thought to labor-producing procedures ought to accompany any pregnancy that runs in the longest 2.5% of all pregnancies. At what day should these procedures be considered?