The length of stay at a specific emergency department in Phoenix, Arizona, in
2009 had a mean of 4.6 hours with a standard deviation of 2.9. Assume that the length of stay is normally distributed.
(a) What is the probability of a length of stay greater than 10 hours?
(b) What length of stay is exceeded by 25% of visits?
(c) From the normally distributed model, what is the probability of a length of stay less than zero hours? Comment on the normally distributed assumption in this example.