Stem & Leaf Plots

Stem & Leaf PlotsObjective:7.4.02 Calculate, use, and interpret the mean, median,

mode, range, frequency distribution, and interquartile range for a set of data.

Essential Question: How can I use stem and leaf plots to organize and display data?

Vocabulary:Stem & Leaf Plot: a graph that uses the digits of each

number to show the shape of the data; each data value is broken down into a “stem” (the digit on the left) and a “leaf” (the digit on the right).

Stem: the greatest place value common to all the data values is used for the stem of a stem and leaf plot.

Leaf: the second greatest place value of data in a stem and leaf plot.

Stem & Leaf Plots

Why Stem and Leaf Plots:- We can use stem and leaf plots to organize large sets of data into one condensed, organized graph

- Later we will use back to back stem and leaf plots to compare multiple sets of data

- Stem and leaf plots provide a visual representation for data

Stem & Leaf Plots

Stem & Leaf PlotsExample 1: Stem & Leaf PlotsUse a stem and leaf plot to graph the following test scores from a recent math test in Mr. Blue’s class:

10

9

8

7

LeafStem

7|0 = 70 %

76, 76, 76, 77, 80, 80, 80, 81, 81, 82, 84, 85, 88, 89, 89, 89, 89, and 92

2

0 0 0 1 1 2 4 5 8 9 9 9 9

6 6 6 7

Stem & Leaf PlotsExample 2: Stem & Leaf PlotsThe table below shows the number of hours spent onboard an airplane for a survey of businessmen and women. Make stem and leaf plot of the data.

4 18 0 23 12 7 935 14 6 11 21 19 615 26 9 0 13 22 10

Hours Aboard an Airplane

3

2

1

0

LeafStem

1|3 = 13 hours5

1 2 3 6

0 1 2 3 4 5 8 9

0 0 4 6 6 7 9 9

Stem & Leaf PlotsExample 3: Stem & Leaf PlotsThe set of data listed below shows the number of home runs Babe Ruth hit during his career from 1914 to 1935. Make a stem and leaf plot to find the mean, median, mode, and range of the data:

Home Run Data: 0, 54, 25, 46, 4, 59, 47, 41, 3, 35, 60, 34, 2, 41, 54, 6, 11, 22, 46, 29, 46, and 49.

Stem & Leaf PlotsExample 3: Stem & Leaf PlotsHome Run Data: 0, 54, 25, 46, 4, 59, 47, 41, 3, 35, 60, 34, 2, 41, 54, 6, 11, 22, 46, 29, 46, and 49.

Stem & Leaf PlotsExample 3: Stem & Leaf PlotsHome Run Data: 0, 54, 25, 46, 4, 59, 47, 41, 3, 35, 60, 34, 2, 41, 54, 6, 11, 22, 46, 29, 46, and 49.

6

5

4

3

2

1

0

LeafStem

2|5 = 25 home runs0

4 4 9

1 1 6 6 6 7 9

4 5

2 5 9

1

0 2 3 4 6Mean32.5

Median38

Mode46

Range60

Example 4: Stem & Leaf PlotsOrganize the following set of data into a stem and leaf plot:

Stem & Leaf Plots

LeafStem

Real World Example:The table shows the average life-span of several mammals. Make a stem and leaf plot to describe the spread and then calculate the measures of central tendency:

Stem & Leaf Plots

Source: The World Almanac

15Zebra10Giraffe20Chimpanzee16Tiger40Elephant12Cat10Squirrel12Dog12Camel3Mouse8Deer20Polar Bear

20Horse15Cow18Black Bear4Guinea Pig6Chipmunk20Baboon

YearsAnimalYearsAnimalYearsAnimal

Real World Example:The table shows the average life-span of several mammals. Make a stem and leaf plot to describe the spread and then calculate the measures of central tendency:

Stem & Leaf Plots

HOMEWORK

Stem & Leaf Plots

Back-to-Back Stem & Leaf Plots

Back-to-Back Stem & Leaf PlotsObjective:7.4.02 Calculate, use, and interpret the mean, median,

mode, range, frequency distribution, and interquartile range for a set of data.

Essential Question: What are some similarities and difference between a stem and leaf and a double stem and leaf plot?

What’s So Great About Them:- Yesterday we used different data to create some stem and leaf plots, which we used to analyze and discuss data trends

- Today we are going to use a different type of stem and leaf plot to analyze data…

ITS CALLED A BACK-TO-BACK STEM AND LEAF PLOT

- We can use these to compare multiple data sources

Back-to-Back Stem & Leaf Plots

Back-to-Back Stem & Leaf PlotsExample 1: Back-to-Back Stem & Leaf PlotsA set of U.S. Olympic Team Track times are listed below. Create a back-to-back stem and leaf plot to compare the men and women's times.

MEN47, 43, 45, 44, 38, 37, 39, 53, 52, 46,

47, and 36

WOMEN57, 53, 55, 54, 48, 47, 49, 53, 52, 46,

47, and 46

Leaf (Men)StemLeaf (Women)

3 45

7 8 9 3 4 5 6 7 73

9 8 7 7 6 67 5 4 3 3 2

Back-to-Back Stem & Leaf PlotsExample 2: Back-to-Back Stem & Leaf PlotsAll the test scores from the recent Percents Unit are listed below. They have broken down by boy and girl scores. Create a Back-to-Back Stem and Leaf Plot to analyze and compare each data set.

BOYS SCORES99, 36, 16, 23, 69, 58, 59, 21, 53, 19, 21, 82, 30, 85, 70, 81, 66, 42,

53, 52, 22, 56, 43, 57, 88, 80, 53, 86, 64, 84, 68, 79, 57, and 82

GIRLS SCORES73, 37, 61, 53, 37, 38, 24, 30, 75, 93, 65, 85, 60, 92, 80, 56, 80, 65,

77, 64, 95, 99, 82, 75, 94, 98, 63, 58, 69, 56, 95, 77, and 45

Back-to-Back Stem & Leaf PlotsLeaf (Girls Data)StemLeaf (Boys Data)

0 123456789

40 7 7 853 6 6 80 1 3 4 5 5 93 5 5 7 70 0 2 52 3 4 5 5 8 9

9 63 2 1 1

6 03 2

9 8 7 7 6 3 3 3 29 8 6 4

9 08 6 5 4 2 2 1 0

9

Back-to-Back Stem & Leaf PlotsExample 2: Back-to-Back Stem & Leaf PlotsWHAT DOES THIS BACK TO BACK STEM AND LEAF PLOT TELL US? WHAT CONCLUSIONS CAN WE MAKE ABOUT THIS DATA.

BOYS SCORES99, 36, 16, 23, 69, 58, 59, 21, 53, 19, 21, 82, 30, 85, 70, 81, 66, 42, 53, 52, 22, 56, 43, 57, 88, 80, 53, 86, 64, 84,

68, 79, 57, and 82

GIRLS SCORES73, 37, 61, 53, 37, 38, 24, 30, 75, 93, 65, 85, 60, 92, 80, 56, 80, 65, 77, 64, 95, 99, 82, 75, 94, 98, 63, 58, 69, 56,

95, 77, and 45

1) The boys data is more spread out – less consistent2) The girls data is more condensed – more consistent3) It looks like the girls were better prepared

HOMEWORK

Back-to-Back Stem & Leaf Plots