Porphyrin is a pigment in blood protoplasm and other body fluids that is significant in body energy and storage. Let x be a random variable that represents the number of milligrams of porphyrin per deciliter of blood. In healthy adults, x is approximately normally distributed with mean σ = 38 and standard deviation σ = 12. What is the probability that:
(a) x is less than 60?
(b) x is greater than 16?
(c) x is between 16 and 60?
(d) x is more than 60 (this may indicate an infection, anemia, or another type of illness)?