Stem-and-Leaf Plot By Mr. Lang

What is a stem-and-leaf plot? A T-chart that is used to show numeric data and the distribution of numbers

Why would I want to use one? It displays a lot of numbers in a neater, cleaner, and organized way. It makes it easier to see how spread out the numbers are It is easier to identify outliers

Reading a Stem-and-Leaf Plot

Things you need to know… Stems The stems include the digits in the tens place and higher

Things you need to know… leaves The leaves are all digits from ONLY the ones place The leaves need to be organized from least to greatest You can have multiples of the same digit per line

Making a Stem-and-Leaf Plot

This stem-and-leaf plot shows points that students received on a science quiz. 40 49 56 58 59 61 64 67 73 75 76 78 80 85 87 88 92 96 100 Stem Leaves 4 9 9 5 6 8 9 6 1 4 7 7 7 7 3 5 6 8 8 5 7 8 9 2 6 10

Finding the Range, Mode, Median, and Mean

Range= biggest number – smallest number 40 is the smallest number 40 49 56 58 59 61 64 67 73 75 76 78 80 85 87 88 92 96 100 Stem Leaves 4 9 9 100 – 40 = 60 The range for this data set is 60 points. 5 6 8 9 6 1 4 7 7 7 7 3 5 6 8 100 is the largest number 8 5 7 8 9 2 6 10 This stem-and-leaf plot shows points that students received on a science quiz.

Finding the Median (the middle number) Start counting with this leaf! 40 49 56 58 59 61 64 67 73 75 76 78 80 85 87 88 92 96 100 Stem Leaves Leaf number 12… This is the halfway point! 4 9 9 I have 23 leaves. If I divided that in half, I would end up with 11.5. This means that the 12th number is my median. 23 ÷ 2 = 11.50  the 12th number will be our median. The twelfth number is 73. This is my median. 5 6 8 9 6 1 4 7 7 7 7 3 5 6 8 8 5 7 8 9 2 6 10 This stem-and-leaf plot shows points that students received on a science quiz.

Finding the Mode (the number that shows up most) You have more 7s than 9s or 0s. That means 67 is your mode. 40 49 56 58 59 61 64 67 73 75 76 78 80 85 87 88 92 96 100 Stem Leaves 4 9 9 For the mode, look at each row of leaves separately. If you see more than one of a number, underline it. After looking at all your rows, pick the underlined number that has the most digits. 5 6 8 9 6 1 4 7 7 7 7 3 5 6 8 8 5 7 8 9 2 6 10 This stem-and-leaf plot shows points that students received on a science quiz.

Finding the Mean (the average) 40 49 56 58 59 61 64 67 73 75 76 78 80 85 87 88 92 96 100 Stem Leaves 4 9 9 To find the mean, you will be doing a combination of Adding and dividing. 5 6 8 9 6 1 4 7 7 7 7 3 5 6 8 8 5 7 8 9 2 6 10 This stem-and-leaf plot shows points that students received on a science quiz.

Finding the Mean (the average) We have 23 leaves. Divide your sum by 23. Stem Leaves 4 9 9 5 6 8 9 1667 ÷ 23 = 6 1 4 7 7 7 7 3 5 6 8 Mean: Approximately 72.48 8 5 7 8 9 2 6 10