This document discusses stem-and-leaf plots and different measures of central tendency including mean, median, and mode. A stem-and-leaf plot arranges data by grouping numbers with the same stem. The mean is found by adding all the numbers and dividing by the total numbers. The median is the middle number when the data is ordered. The mode is the number that occurs most frequently and data can have no mode or more than one mode. Examples are provided to calculate and interpret the mean, median, and mode of sample data sets.

1. Algebra 1
6.6 Stem-and-Leaf Plots and Mean, Median, and Mode
Stem-and-Leaf Plot
Arrangement of ____________________ used to display and order data.
• All of the “stems” are the ________________________________ of the numbers.
• All of the _______________________ are the second digits.
o These are listed with all the other _______________ of the same stem.
EX1: The following data show the ages of the residents of Alcan, Alaska. Make a
stem-and-leaf plot to display the data.
45 1 52 42 10 40 50 40 7
46 19 35 3 11 31 6 41 12
43 37 8 41 48 42 55 30 58
Unordered: Ordered:
There is more than one way to describe something that is “average” or “typical.”
Mean (Also called _______________________)
• ______________ all the numbers together, then divide by ___________________
numbers you have.
Median
• The ______________________________________ of all the numbers when the
set is written in order.
• If there are two middle numbers, _____________________ those numbers.
Mode
• The numbers that occur ________________________________________.
• A set can have no mode or ________________________________ mode.

2. EX2: Find the (a) mean, (b) median, and (c) mode of the data in Example 1.
EX3: Find the (a) mean, (b) median, and (c) mode of the data represented in the graph.
Sometimes the mean is more ____________________________ of the data. Other times,
especially if the data is very ____________________, the median or the mode is a better
choice.
HW p. 371 (12 – 24 even, 25 – 31 all)