1.
(to receive full credit you must include a
sketch of the normal model, show your calculations, clearly distinguish between
z-scores and probability, use correct probability notation, and provide a
solution statement referring back to the problem context).

The
lengths of human pregnancies are normally distributed with a mean length of 281
days and standard deviation of 13 days.

WHAT LENGTH OF PREGNANCY WOULD BE THE 40TH PERCENTILE?