Chapter 6 – Solving and Graphing Linear Inequalities

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode.

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

Today we will be: Making and using a stem-and-leaf plot to

put data in order

Finding the mean, median, and mode of data

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

A stem-and-leaf plot is an arrangement of digits that is used to display and order numerical data.

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

Example 1The following data show the ages of the 27 residents of Alcan, Alaska. Make a stem-and-leaf plot to display the data.

45 1 52 4210 40 50 407 46 19 353 11 31 641 12 43 378 41 48 4255 30 58

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

Example 1 Use digits in the

tens’ place for the stems

Use digits in the ones’ place for the leaves

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

You can order the leaves to make an ordered stem-and-leaf plot.

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

A measure of central tendency is a number that is used to represent a typical number in a data set.

There are three commonly used measures of central tendency: Mean Median Mode

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

The mean, or average, of n numbers is the sum of the numbers divided by n

The median of n numbers is the middle number when the numbers are written in order. If n is even, the median is taken to be the

average of the two middle numbers. The mode of n numbers is the number that

occurs most frequently. A set of data can have more than one mode or

no mode.

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

Example 2Find the measure of central tendency of the ages of the residents of Alcan, Alaska (from Example 1). Mean Median Mode

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

Many collections of numbers in real life have graphs that are bell shaped. For those such collections, the mean,

median and mode are about equal.

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

Example 3A ski area surveyed 131season pass holders to see how many days they had skied the previous season. Responses are shown in the histogram. Find the median and the mode of the data.

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

Example 4

A teacher presents a lesson two ways, each with a different group of students. The first group scores 8, 3, 5, 3, and 9 on a quiz; the second group scores 5, 6, 1, 5, and 4. Using measures of central tendency, do you think one group did better than the other? Explain.

6.6 – Stem-and-Leaf Plots and Mean, Median, and Mode

HOMEWORK

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