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## 7-4

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**7-4**Statistical Graphs**WHAT YOU WILL LEARN**• To display data into: Histograms Frequency polygons Stem-and-leaf displays**Circle Graphs**• Circle graphs (also known as pie charts) are often used to compare parts of one or more components of the whole to the whole.**Example**• According to a recent hospital survey of 200 patients, the following table indicates how often hospitals used four different kinds of painkillers. Use the information to construct a circle graph illustrating the percent each painkiller was used. Aspirin 56 Ibuprofen 104 Acetaminophen 16 Other 24 200**Painkiller**Number of Patients Percent of Total Measure of Central Angle Aspirin 56 0.28 360 = 100.8 Ibuprofen 104 0.52 360 = 187.2 Acetaminophen 16 0.08 360 = 28.8 Other 24 0.12 360 = 43.2 Total 200 100% 360 Solution • Determine the measure of the corresponding central angle.**Hospital Painkiller Use**Ibuprofen 52% Aspirin 28% Other Acetaminophen 12% 8% Solution (continued) • Use a protractor to construct a circle graph and label it properly.**# of pets**Frequency 0 6 1 10 2 8 3 4 4 2 Histogram • A histogram is a graph with observed values on its horizontal scale and frequencies on it vertical scale. • Example: Construct a histogram of the frequency distribution.**# of pets**Frequency 0 6 1 10 2 8 3 4 4 2 Solution**Frequency Polygon**• A frequency polygon is a line graph with observed values on its horizontal scale and frequencies on it vertical scale.**Stem-and-Leaf Display**• A stem-and-leaf display is a tool that organizes and groups the data while allowing us to see the actual values that make up the data. • The left group of digits is called the stem. • The right group of digits is called the leaf.**12**18 3 8 12 25 21 3 15 4 17 27 43 21 16 12 26 35 14 9 Example • The table below indicates the number of miles 20 workers have to drive to work. Construct a stem-and-leaf display.**Data**Stem-and-Leaf 0 3 3 4 8 9 12 18 3 8 12 25 21 3 15 4 1 2 2 2 4 5 6 7 8 17 27 43 21 16 2 1 1 5 6 7 12 26 35 14 9 3 5 4 3 Solution**Frequency**Frequency Frequency Frequency Class Class Class Class Construct a histogram of the frequency distribution. a. c. b. d.**Frequency**Frequency Frequency Frequency Class Class Class Class Construct a histogram of the frequency distribution. a. c. b. d.**Frequency**Frequency Frequency Frequency Class Class Class Class Construct a frequency polygon of the distribution. a. c. b. d.**Frequency**Frequency Frequency Frequency Class Class Class Class Construct a frequency polygon of the distribution. a. c. b. d.