Lesson Menu Main Idea and New Vocabulary Key Concept:Using Mean, Median, and Mode Example 1:Choose an Appropriate Measure Example 2:Choose the Appropriate Measure Example 3:Choose the Appropriate Measure Example 4:Choose the Appropriate Measure

Main Idea/Vocabulary Choose an appropriate measure of central tendency. Identify outliers. outlier

Key Concept

Example 1 Choose an Appropriate Measure SEA TURTLES The table shows the total number of sea turtles observed at four sea turtle research sites on the eastern coast of Florida. Which measure of central tendency best represents the data? Find that measure of central tendency.

Example 1 Since the set of data has an extreme value, 207, and no repeated values, the median would best represent the data. Choose an Appropriate Measure 207 1,033 1,231 1,332 Answer: The median number of sea turtles observed is 1,132.

Example 1 CYP A.mean; $4.69 B.median; $4.38 C.mode; $4.75 D.mode; $4.50 SANDWICHES The prices of several sandwiches are $4.50, $4.75, $4.50, $4.25, $4.50, $4.50, $5.75, and $4.75. Which measure of central tendency best represents the data? Find that measure of central tendency.

Example 2 ANIMALS The table shows the number of threatened species in the United States in Identify the outlier in the data set. Compared to the other values, 43 is extremely high. Choose the Appropriate Measure Answer: So, the outlier is 43.

Example 2 CYP A.53° B.75° C.78° D.83° WEATHER The daily high temperatures for one week were 78°, 75°, 53°, 75°, 79°, 83°, and 76°. Identify the outlier in the set.

Example 3 Choose the Appropriate Measure ANIMALS The table shows the number of threatened species in the United States in Determine how the outlier affects the mean, median, and mode of the data. Find the mean, median, and mode with and without the outlier.

Example 3 With the outlier Choose the Appropriate Measure Median11 Mode9 and 11 Without the outlier Median10 Mode9 and 11

Example 3 Answer:The mean decreased by 15 – 10 or 5. The median decreased by 1. The mode did not change. Choose the Appropriate Measure

Example 3 CYP A.mean: decreased by about 3.5; median: increased by 1; mode: no change B.mean: increased by about 3.5; median: increased by 1; mode: no change C.mean: increased by about 3.5; median: decreased by 1; mode: no change D.mean: decreased by about 3.5; median: no change; mode: no change WEATHER The daily high temperatures for one week were 78°, 75°, 53°, 75°, 79°, 83°, and 76°. Determine how the outlier affects the mean, median, and mode of the data.

Example 4 ANIMALS The table shows the number of threatened species in the United States in Which measure of central tendency best describes the data with and without the outlier? The mean with the outlier is 15 and without the outlier is 10. Choose the Appropriate Measure

Example 4 The median with the outlier is 11 and without the outlier is 10. The modes were 9 and 11 both with and without the outlier. The mean was affected the most with the outlier. The median changed very little with and without the outlier. The modes do not describe the data very well since there were only two repeated numbers. Choose the Appropriate Measure Answer: The median best describes the data since it changed very little with and without the outlier.

Example 4 CYP A.The mean best describes the data because it changed very little with and without the outlier. B.The median best describes the data because it changed very little with and without the outlier. C.The mode best describes the data because there are two repeated numbers. WEATHER The daily high temperatures for one week were 78°, 75°, 53°, 75°, 79°, 83°, and 76°. Which measure of central tendency best describes the data with and without the outlier? Justify your selection.

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