Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

Exercise 115

Vital Statistics: Heights of Men The heights of 18 year old men are approximately normally distributed, with mean 68 inches and standard deviation 3 inches (based on information from Statistical Abstract of the United States , 112th Edition).
(a) What is the probability that an 18 year old man selected at random is between 67 and 69 inches tall
(b) If a random sample of nine 18 year old men is selected, what is the probability that the mean height
is between 67 and 69 inches
(c) Interpretation Compare your answers to parts (a) and (b). Is the probability in part (b) much higher Why would you expect this