Chapter 1 Section 8

1
Chapter 1 Section 8

• Box and Whisker Plots

2
5-MINUTE WARM-UP

• Find the mean, median, mode, and range.
• A. 10 7 7 9 10 8 11 12 10 8
• B. 9.1 8.7 9.2 9.0 8.7 8.9 15.0
  9.2
• Answers
• A. 9.3, 10, 10, 5
• B. 9.7, 9.5, 8.7 and 9.2, 6.3

3

• Box and Whiskers Plots

5 10 15 20 25 30 35 40 45 50 55 60
4
Box-and-Whisker Plots

• Box-and-whisker plots identify trends and
  summarize information.

• The distribution of data is divided into four
  equal parts.
• The three numbers that separate a set of data
  into these four parts are called quartiles.
• The box represents the middle 50 of the data.

5 10 15 20 25 30 35 40 45 50 55 60
5
Hank Aaron's home run data.
1967 39 1968 29 1969 44 1970
38 1971 47 1972 34 1973 40
1974 20 1975 12 1976 10
1954 13 1955 27 1956 26 1957
44 1958 30 1959 39 1960
40 1961 34 1962 45 1963 44 1964
24 1965 32 1966 44
6
Steps to making a box-and-whisker plot for
Aarons homeruns

• Arrange the data in numerical order and find the
  median.
• The median of the data set is the second
  quartile.
• Identify the median of the lower half of the
  data, which is the first quartile.
• The median of the upper half of the data is the
  third quartile.

• Greatest Value

• Least Value

10 12 13 20 24 26 27 29 30 32 34 34 38 39 39 40
40 44 44 44 44 45 47

• Median
• Second Quartile

• First Quartile

• Third Quartile

7
Above a number line, graph the median, the first
and third quartiles, the least value and the
greatest value.

• Draw a box from the first quartile to the third
  quartile.
• Draw a vertical line at the median.
• Draw horizontal lines to connect the least value
  to the first quartile and the greatest value to
  the third quartile.
• These lines are called whiskers.
• Label the box-and-whisker plot.

• Hank Aaron's Career Home Runs

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8
Carbohydrates in Cereal

• Make a box and whiskers of the percentage of
  carbohydrates in brands of cereal.
• Data

9
Step 1

• Arrange the data in numerical order.

• 3 5 8 21 22 26 30 32 32 33 36 37 38 40 40 41 42
  42 44 44 46 48 55 56

10
Step 2

• Find the median.
• The median of the data set is the second
  quartile.

• 3 5 8 21 22 26 30 32 32 33 36 37 38 40 40 41 42
  42 44 44 46 48 55 56

11
Step 3

• Identify the median of the lower half of the
  data, which is the first quartile.

• 3 5 8 21 22 26 30 32 32 33 36 37 38 40 40 41 42
  42 44 44 46 48 55 56

12
Step 4

• Identify the median of the upper half of the data
  which is the third quartile.

• 3 5 8 21 22 26 30 32 32 33 36 37 38 40 40 41 42
  42 44 44 46 48 55 56

13
Step 5

• Make a number line for the data

0 10 20 30 40 50 60
14
Step 6

• Draw a box from the first quartile to the third
  quartile.

15
Step 7

• Draw a vertical line at the median.

16
Step 8

• Draw horizontal lines to connect the least value
  to the first quartile and the greatest value to
  the third quartile.

17
Step 9

• Give the box and whiskers plot a title.

• Percent of Carbohydrates