Notes Period: ______Date: ______
TOPIC: Mean, Median, Mode, Range; Stem-and-Leaf Plot
Objective / Given a data set, learn how to calculate the mean, median, mode and range of that data set and also create a stem-and-leaf plot for that data set.
Vocabulary / data set: a group of numbers that represents information about something.
data point: ONE of the numbers in the data set is called a data point.
SUMMARIZING DATA WITH MEAN, MEDIAN, MODE, and RANGE
It is difficult to read and understand large data sets (groups of numbers).That is why we summarize data by calculating the mean, median, mode, and range:
For these, write the numbers in order from smallest to biggest
mean / median / mode / range
Add all the data point values together, and then divide by the number of data points you have.
Sometimes also called average. / The middle value of the list of numbers placed in order.
(Or, the average of the two middle values) / Many numbers can repeat in a data set, but the mode is the number(s) that repeat the most. / Subtract the largest data point minus the smallest data point.
Example:
This is a data set of the ages of people at a meeting:
8 / 9 / 9 / 27 / 9 / 7 / 9 / 8 / 9 / 8 / 9
1) What is the mean (average) of this data set? ______
(Show your work below)
2) What is the median of this data set? ______
3) What is the mode of this data set? ______
(Remember: mode is the one that repeats the most.)
4) What is the range of this data set? ______
(Remember: biggest minus smallest value)
SPECIAL CASES
Median – Sometimes the median of a data set is the average of the two middle numbers.Example: Find the median of the data set 3, 5, 8, 3, 4, 6, 4, 5
Mode – Sometimes a data set can have more than one mode.
Example: Find the mode of the data set 10, 14, 15, 10, 12, 15, 13, 14, 10, 14
STEM – and – LEAF PLOT
A stem-and-leaf plot is a special table we can use to organize large data sets more neatly.
In the “stem” part write the tens digit and in the “leaf” part write the ones digits.
Example: Create a stem-and-leaf plot for the data set:
stem leaf
Mean: ______
Mode: ______
Median: ______
Range: ______
Now You Try!
Create a Stem-and-Leaf Plot with the following data set:
67, 62, 10, 3, 12, 34, 51, 4, 10, 13, 48, 55, 9, 10, 15, 32, 49
Mean: ______
Mode: ______
Median: ______
Range: ______