13.17 Horse pregnancies. 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 of three days. Use the 68–95–99.7 rule to answer the following questions.
(a) Between what values do the lengths of the middle 95% of all horse pregnancies fall?
(b) What percentage of horse pregnancies are less than 333 days?