Dot Plots and Measures of Center Teacher Twins

Warm Up Find the mean, median, mode and range for each set of data.

A dot plot shows the frequency of data on a number line. It is

The distribution of a dot plot shows the arrangement of the values of a

A dot plot is skewed right if most of the data are clustered to

A dot plot is skewed left if most of the data are clustered to

Measures of Center Data sets have many numerical values. You can summarize the data

Example 1: Which measure of center would best represent this data? How many books

Example 2: Which measure of center would best represent this data? Science Test Grades

Practice Find each measure of center and tell which best represents the data. 1).

Closure Why do we need to use measures of center such as the mean

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Warm Up Find the mean, median, mode and range for each set of data. 1). 45, 67, 34, 43 , 56, 67 52, 50. 5, 67, 33 202, 234, ( 121, 234), 179 2). 121, 234, 300, 121, 234 3). 34, 67, 87, 23, 12, 98, 56 53. 8, 56, none, 86

A dot plot shows the frequency of data on a number line. It is best to use a dot plot when you do not have a lot of data. X 4 5 X X X X X 6 7 8 9 10

The distribution of a dot plot shows the arrangement of the values of a data set. A symmetrical graph shows the same number of points below and above the middle point. How many books did you read over the summer? X X X X 4 5 6 7 8 9 10 This graph is symmetrical.

A dot plot is skewed right if most of the data are clustered to the left or the lower data values. How many books did you read over the summer? X X X X X 4 5 6 X X X 7 8 9 10

A dot plot is skewed left if most of the data are clustered to the right or the higher values. How many books did you read over the summer? Gap X X X 4 5 6 7 Peak X X X Cluster 8 9 X X 10

Measures of Center Data sets have many numerical values. You can summarize the data with one number called a measure of center. Mean and median are measures of center. The median is a more useful measure of center if the data is skewed.

Example 1: Which measure of center would best represent this data? How many books did you read over the summer? X X X X 4 5 6 7 8 9 10 Mean-7. 9 Median-8. 5 The median best represents the data because it is skewed.

Example 2: Which measure of center would best represent this data? Science Test Grades X X X X 40 50 60 70 80 90 100 Mean-70 Median-70 The median and mode best represents the data because it is not skewed.

Practice Find each measure of center and tell which best represents the data. 1). How many brothers and sisters do you have? Mean-2. 4 Median-1. 5 X The median best 0 1 2 3 4 5 6 7 8 9 10 represents the data 2). How many pets do you have? because it is skewed. X X Mean-2. 8 X X X Median-3 X X X Both represent the 0 1 2 3 4 5 6 7 data because the graph is symmetrical. X X X XX

Closure Why do we need to use measures of center such as the mean and median to represent data? It summarizes the data in one number.