1A.2 Dot Plots and Measures of Dispersion
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Transcript of 1A.2 Dot Plots and Measures of Dispersion
1A.2 Dot Plots and
Measures of Dispersion
Vocabulary
Dot PlotA graph that shows the frequency of values in a data set
Measure of DispersionA measure that describes the spread of a data set
To Create a Dot Plot: 1) Find the minimum and maximum value in your data set.
2) Draw a number line going from the minimum value to the maximum value.
3) Place a dot above the number on the number line for each number in your data set. If there is already a dot above the number, add an additional dot above the existing one.
When you are finished there should be a dot on the graph for each piece of data in the data set.
Draw a dot plot of the data and then find the mean, median and mode of the data.
Bag 1 2 3 4 5 6 7 8 9
Strawberries 10 13 11 15 8 14 7 11 12
Find the mean, median, mode and range for the dot plot
Directions: Make a double dot plot for the data below.
Points in ten baseball games
Hall HS: 4, 4, 6, 6, 8, 3, 3, 2, 1, 1
Conard HS: 2, 4, 8, 9, 5, 5, 1, 1, 2, 0
1.) 2.)
After the first week, the 25-year-old is voted off Show A and the 48-year-old is voted off Show B. How does this affect the mean and range of the remaining contestants on each show?
Standard DeviationThe standard deviation of a data set is a measure of how much a typical value in the data set differs from the mean.
standard deviation n
xxxxxx n22
22
1 )()()(
• where n is the number of values in the data set• the symbol represents the mean. It is read as “x-
bar”
20 25
29 25
19 25
22 25
25 25
27 25
27 25
29 25
30 25
20 25
21 25
31 25
x xx 2)( xx x
Find the standard deviation of the ages for Show B in Example 1. Interpret your results.
x xx 2)( xx x
You are the general manager of an NBA team. You are 35 games into the season and you are planning to sign a new player. You are choosing between player X and player Y. The points they have scored in every game so far are shown in the dot plots below. If you could sign player Y for 4 million dollars, how much more would you be willing to pay player X? Why? Justify your answer with calculations, using the ideas of center and spread.
Player X – Points per game
Player Y – Points per game