Practice and Problem-Solving Exercises

A Practice

See Problem 1.

Biology The heights of men in a survey are normally distributed about the mean. Use the graph for Exercises 7–10.

7. About what percent of men aged 25 to 34 are 69–71 in. tall?
8. About what percent of men aged 25 to 34 are less than 70 in. tall?
9. Suppose the survey included data on 100 men. About how many would you expect to be 69–71 in. tall?
10. The mean of the data is 70, and the standard deviation is 2.5. Approximately what percent of men are within one standard deviation of the mean height?

Image Long Description

See Problem 2.

Sketch a normal curve for each distribution. Label the x-axis values at one, two, and three standard deviations from the mean.

11. mean = 45, standard deviation = 5
12. mean = 45, standard deviation = 10
13. mean = 45, standard deviation = 2
14. mean = 45, standard deviation = 3.5

See Problem 3.

A set of data has a normal distribution with a mean of 50 and a standard deviation of 8. Find the percent of data within each interval.

15. from 42 to 58
16. greater than 34
17. less than 50

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