The waist circumference of males 20 to 29 years old is approximately normally distributed, with mean 92.5 cm and standard deviation 13.7 cm.
(a) Use the normal model to determine the proportion of 20- to 29-year-old males whose waist circumference is less than 100 cm.
(b) What is the probability that a randomly selected 20- to 29- year-old male has a waist circumference between 80 and 100 cm?
(c) Determine the waist circumferences that represent the middle 90% of all waist circumferences.
(d) Determine the waist circumference that is at the 10th percentile.