Stem and Leaf Plot

When there are many numbers in a set of data, we can construct a stem-and-leaf plot to show the data and make it easier to read.

Drawing a stem-and-leaf plot

Example :

Construct a stem-and-leaf plot for the following set of data.

28 13 26 12 20 14 21 16 17 22
17 25 13 30 13 22 15 21 18 18
16 21 18 31 15 19

Solution:

Step 1: Find the least number and the greatest number in the data set.

The greatest number is 31 (3 in the tens place)

The smallest number is 12 (1 in the tens place)

Step 2: Draw a vertical line and write the digits in the tens places from 1 to 3 on the left of the line. The tens digit form the stems.

Step 3: Write the units digit to the right of the line. The units digits form the leaves.

Step 4: Rewrite the units digits in each row from the least to the greatest.

Step 5: Include an explanation.

Interpret a stem-and-leaf plot

Example:

The following stem-and-leaf plot shows the ages of a group of people in a room.

a) How many people were there in the room?

b) Two people have the same age. What is that age?

b) What is the mode, median and mean of the ages?

Solution:

a) We count the number of digits on the right of the line (leaves). There were 12 people in the room.

b) The two people were 22 years old.

c)

The mode is 22.

The median can be obtained from the average 6th and 7th data.

The average of 22 and 24 is 23.

The median age is 23

To get the mean, we have to first get the total ages.

17 + 18 + 19 + 20 + 22 + 22 + 24 + 25 + 26 + 41 + 42 + 44 = 320

The mean = = 26.67

The following video will show to create stem-and-leaf plots or frequency tables using given data, and answer questions based on given stem-and-leaf plots or frequency tables

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