13.12 Horse pregnancies. Bigger animals tend to carry their young longer before birth. The length of horse pregnancies om 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) 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