A Survey of Mathematics Related Topics: Pg. 681 - 682, Example 6

Stem-and-Leaf plots are used to analyze sets of data and are especially helpful when finding the following values:

• Mean: the sum of all the data points divided by the number of items, also known as the average.
• Median: the number in the middle when the data set is arranged in increasing order.
• Mode: the number that appears most frequently in the data.

A Stem-and-Leaf plot is much like a histogram, displaying the number of times that an event within a particular range occurs. Yet, the stem-and-leaf plots reveals a little more information than a histogram, and it can show the exact data points. It is constructed by placing the first number of each data point on the left hand side of the line, and the remaining digits on the right-hand side on the line.

If we were to make a stem-and-leaf plot of a set of grades on the last test in my math class, it might look something like this:

This shows that there are 27 people in my class. One person failed the test, making a grade of 37, and three people made D's: 66, 68, and 69. There were 6 C's: 74, 74, 75, 76, 79, and 79; 10 B's: 82, 83, 83, 83, 85, 85, 86, 87, 87, 88; and 6 A's: 90, 91, 92, 97, 98, 99, and 100.

With this chart, calculating the mean, median, and mode will be much easier!