Length of Pregnancy. A woman wrote to Dear Abby and claimed that she gave birth 308 days after a visit from her husband, who was in the Navy. Kengths of pregnancies have a mean of 268 days and a standard deviation of 15 days, Find the z score for 308 days. Is such a length unusual? What do you conclude?
(a) M = 268, SD = 15, x = 308
z = (x - M)/SD
z = (308 - 268)/15 = 2.667
Neat, step-wise solution is provided.