The heights of adult American males are approximately normally distributed with mean 69.5 in. and standard deviation 2.5 in.
What percent of adult American males are between 67 in. and 74.5 in. tall?
How do you divide the graph of the distribution?
Draw vertical lines at intervals that are one standard deviation wide, on both sides of the mean.
Draw a normal curve. Label the mean. Divide the graph into sections of standard-deviation widths. Label the percentages for each section.
Distribution of Heights—Adult American Males
About 82% of adult American males are between 67 in. and 74.5 in. tall.
In a group of 2000 adult American males, about how many would you expect to be taller than 6 ft (or 72 in.)?
Because the graph is symmetric about the mean, the right half of the distribution contains 50% of the data. If you subtract everything between 69.5 in. and 72 in. from the right half, only the part of the distribution that is greater than 72 in. remains.
Distribution of Heights—Adult American Males
You would expect about 16% of the 2000 adult American males to be taller than 72 in.
You would expect about