mean human gestation period is 266 days. Actual time to delivery is
approximately normally distributed with a standard deviation of about 12 days.
Marcelle goes into labor and gives birth to a child 245 days after conception.
What percentage of women give birth (a) at the same point in pregnancy as or
earlier than Marcelle, (b) at a later point in pregnancy than Marcelle, and (c)
between their due date and the point at which Marcelle gave birth?