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Unit 9 Lesson 5 Measures of Center-STEM AND LEAF
PLOTS
Vocabulary
•Leaf – the last number
•Stem – anything to the left of the very last number
(sometimes that is “0” ; sometimes it is two numbers)
•Key – an explanation of the stem and leaf
High temperatures for the last week: 72, 78, 87, 90, 88, 86, 87, 89
Stem
7
8
9
Leaf
2 8
6 7 7 8 9
07 2 = 72 degrees
Stem and Leaf Plot
• Here are the numbers of homeruns that Babe Ruth hit in each of his 15 years with the New York Yankees from 1920-1934:
– 54, 59, 35, 41, 46, 25, 47, 60, 54, 46, 49, 46, 41, 34, 22
2 3 6 7 8 9 9
0 0 1 1 1 1 2 2 4 4 4 4 5 5 5 6 6 6 7 7 7 7 8
0 1 1 1 2 4 4 5 8 9
Stem Leaf
4
5
6
Age of United states Presidents at their First Inauguration: 57 61 57 57 58 57 61 54 68 51 49 64 50 48 65 52 56 46 54 49 50 47 55 54 42 51 56 55 51 54 51 60 62 43 55 56 61 52 69 64 (Through the 40th presidency)
Key: 5 7 means 57Key: 5 7 means 57
Stem and Leaf Diagrams
How to Draw One:
1. Put the first digits of each piece of data in numerical order down the left-hand side
2. Go through each piece of data in turn and put the remaining digits in the proper row
3. Re-draw the diagram putting the pieces of data in the right order
4. Add a key
Stem and Leaf Diagrams
Remember: - Always put in a Key- Always put your data in Order
Median:- to work out the median, you must find the middle value- if there are two middle values, you need the average
Range:- to work out the Range, subtract the smallest number from the biggest
Stem and Leaf Diagrams
The stem & leaf diagram below shows the masses in kg of some people in a lift.
(a) How many people were weighed?
(b) What is the range of the masses?
(c) Find the median mass.
Stem Leaf3
4
5
6
7
8
1 4
3 3 6
0 3 4 8
1
2 2 7
1 6
2
tens units
(a) 16 people.(b) 86 – 31 =
55 kg
Median is the mean of the
8th and 9th data values.
(c) 56 kg
Using Stem-and-Leaf Plots
• What was the least number of cookies sold?
Boxes of Girl Scout Cookies Sold by Troop 220
40 boxes
Using Stem-and-Leaf Plots
• What was the largest number of cookies sold?
Boxes of Girl Scout Cookies Sold by Troop 220
94 boxes
Using Stem-and-Leaf Plots
• Find the median of the data
Find the middle leaf…
63 boxes
Boxes of Girl Scout Cookies Sold by Troop 220
Using Stem-and-Leaf Plots
• Find the mode of the data Look for the number that occurs
most often in a row of leaves 63 boxes
Boxes of Girl Scout Cookies Sold by Troop 220
Practice
• Pages 323 and 323
• #1-16
