5.The length of a particular animal's pregnancies are approximately normally distributed, with mean and standard deviation . You must show all computations. You must write the probabilities in the correct notations and symbols. You must sketch the normal probabilities as indicated.

a)What proportion of pregnancies lasts more than 270 days?

b)What proportion of pregnancies lasts between 254 and 268 days?

c)What is the probability that a randomly selected pregnancy lasts no more than 256 days?

d)What length of pregnancy for this particular animal, separates the lowest 20%? In other words, what is the 20^th percentile?

e)A "very preterm" baby is one whose gestation period is less than 246 days. Are "very preterm babies" unusual? Why?