pls help with hw question

Homework: HW Question 22, 7.2. HW Score: 60.71%, 17 of 28 points Part 1 of 4 O Points: 0 of 1 The lengths of a particular animal's pregnancies are approximately normally distributed, with mean u = 263 days and standard deviation o = 20 days. (a) What proportion of pregnancies lasts more than 288 days? (b) What proportion of pregnancies lasts between 238 and 273 days? (c) What is the probability that a randomly selected pregnancy lasts no more than 233 days? (d) A "very preterm" baby is one whose gestation period is less than 218 days. Are very preterm babies unusual? (a) The proportion of pregnancies that last more than 288 days is