Transcript Lesson 3-3a

3-3
6th grade math
Stem-and-Leaf Plots
Objective
• To use stem-and-leaf plots to analyze central
tendencies of data with 2 or 3 digit numbers.
• Why? To know another way to analyze data.
It is a quick way to show numeric data and
study its distribution.
California State Standards
MR 2.4: Use a variety of methods, such as …
graphs, tables, … and models, to explain
mathematical reasoning.
SDP 1.2: Understand how additional data added to
data sets may affect these computations of
measures of central tendency.
SDP 1.4: Know why a specific measure of central
tendency (mean, median, mode) provides the
most useful information in a given context.
How to Set Up a Stem-and-Leaf
Plot Graph to 2 Digit Data
56, 70, 98, 92, 72, 85, 80, 85, 89,
81, 104, 96:
1) List the tens digits in a column
from the least to greatest. STEM
2) Next draw a vertical line to the
right of this column.
3) LEAVES: Then for each number
in the set, the ones digit is
placed after the appropriate
tens digit. These digits are listed
from least to greatest and are
repeated for duplicate numbers
occurring in the set. It should
resemble a bar graph.
4) Title the Graph
56, 70, 98, 92, 72, 85, 80, 85, 89,
81, 104, 96:
Stem
Leaves
5
6
6
7
0, 2
8
0, 1, 5, 5, 9
9
2, 6, 8
10
4
How to Find Median Using Stem-andLeaf Plots
The median can be found
by counting from either
end of the plot until the
center is found. If there
are an even number of
data values, the two
center numbers are
averaged.
Stem
Leaves
5
6
6
7
0, 2
8
0, 1, 5, 5, 9
9
2, 6, 8
10
4
85 = median
How to Find Mode Using Stem-andLeaf Plots
The mode is easily
determined by noting
which number occurs
most often.
Stem
Leaves
5
6
6
7
0, 2
8
0, 1, 5, 5, 9
9
2, 6, 8
10
4
Mode = 85
How to Find Mean Using Stem-andLeaf Plots
You will still need to find
the average of all the
numbers in the set.
Add to find its total and
then divide by the
quantity in the set.
Stem
Leaves
5
6
6
7
0, 2
8
0, 1, 5, 5, 9
9
2, 6, 8
10
4
Total = 1008 ÷ 12 = 84
How to Find Range Using Stem-andLeaf Plots
Stem
Leaves
Use the same rules to find
the range.
Subtract the least number
in the set from the
greatest number.
5
6
6
7
0, 2
8
0, 1, 5, 5, 9
9
2, 6, 8
10
4
104 – 56 = 48
Range = 48 numbers in the
data set
Putting all the information together.
• Median = 85
• Mode = 85
• Mean = 84
• Statistically: the data is relevant.
Try It!
Use the Stem-and-Leaf
Plot to find
1) The range
2) The median
3) The mode
Stem
Leaves
0
7
1
4, 8
2
3, 8
3
3, 5
4
0, 2, 5, 6
1) Range = 46 – 7 = 39
2) Median = 33
3) Mode = none
Objective Review
• To use stem-and-leaf
plots to analyze central
tendencies of data with
2 or 3 digit numbers.
• Why? You now know
another way to analyze
data. It is a quick way to
show numeric data and
study its distribution.
Independent Practice
• Complete problems 510
• Follow all directions
• Show all work!
• If time, complete Mixed
Review: 11-14
• If still more time, work
on Accelerated Math.