B Apply

14. Find the standard deviation for each data set. Use the standard deviations to compare each pair of data sets.

    fastest recorded speeds of various large wild cats (miles per hour):

    70 50 30 40 35 30 30 40 15

    fastest recorded speeds of various birds in flight (miles per hour):

    217 106 95 56 65 37 50 31 53 25 25 25

15. Think About a Plan Use the data for daily energy usage of a small town during ten days in June. Find the mean and the standard deviation of the data. How many values in the data set fall within one standard deviation from the mean? Within two standard deviations? Within three standard deviations?

    51.8 MWh	53.6 MWh	54.7 MWh	51.9 MWh	49.3 MWh
    52.0 MWh	53.5 MWh	51.2 MWh	60.7 MWh	59.3 MWh

    • How is the mean of the data set used in the formula for standard deviation?
    • How can a table help you find the standard deviation?
    • How can a graph help you decide how many standard deviations a data value is from the mean?

Income Use the chart below for Exercises 16–18.

SOURCE: U.S. Department of Agriculture

16. Find the mean income for each year.
17. Writing Use the standard deviation for each year to describe how farm income varied from 2001 to 2002.
18. For 2001, the farm incomes of which states are not within one standard deviation of the mean?
19. 1. Data Collection Make a table showing the number of siblings of each student in your class.
    2. Find the mean and standard deviation of the data.

20. Energy The data for daily energy usage of a small town during ten days in January is shown.

    83.8 MWh	87.1 MWh	92.5 MWh	80.6 MWh	82.4 MWh
    77.6 MWh	78.9 MWh	78.2 MWh	81.8 MWh	80.1 MWh

    1. Find the mean and the standard deviation of the data.
    2. How many values in the data set fall within one standard deviation from the mean? Within two standard deviations? Within three standard deviations?

21. Error Analysis One of your friends says that the data below fall within three standard deviations from the mean. Your other friend disagrees, saying that the data fall within six standard deviations from the mean. With whom do you agree? Explain.

    
    Image Long Description

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