Horse pregnancies are longer. Bigger animals tend to carry their young longer before birth. The length of horse pregnancies from conception to birth varies according to a roughly Normal distribution with mean 336 days and standard deviation 3 days. Use the 68-95-99.7 rule to answer the following questions.
(a) Almost all (99.7%) horse pregnancies fall in what range of lengths?
(b) What percent of horse pregnancies are longer than 339 days?