Dot Plot
Concept
A dot plot is used to represent any data in the form of dots or small circles. It is similar to a simplified histogram or a bar graph as the height of the bar formed with dots represents the numerical value of each variable. Dot plots are used to represent small amounts of data.
Rules
It is best to use a dot plot when comparing fewer than 25 numbers.
To make a dot plot out of given data, determine a scale that includes all of the data in appropriate intervals. Then plot each number using dots or other marks to show the frequency.
Example
The number of pages in a variety of children’s books are given below. Use the data to create a line plot.
Solution
1. Determine a scale that includes all of the data in appropriate intervals.
2. Then count how many times each number appears in the frequency table and plot each number using dots or other marks to show the frequency.
13 = 2, 14 = 2, 15 = 2, 16 = 2, 17 = 3, 19 = 4
Practice Dot Plot
Practice Problem 1
A class of students was asked how many hours of sleep they usually get on a school night. The data collected is represented in the line plot below. Use the line plot to answer the given question.
What was the least number of hours of sleep?
Practice Problem 2
The heights of 20 basketball players, in inches, are given below. Answer the following question based on the given data.
68, 70, 70, 71, 75, 80, 81, 82, 84, 75
75, 80, 75, 77, 75, 80, 83, 80, 71, 70
When creating a line plot to represent the data, what would be the highest number on the number line?
Practice Problem 3
Hector measured the height of the tree saplings on his tree farm. He recorded the data in the chart below. Use the data to create a line plot.
A dot plot is a graph that shows the frequency of data along a number line using dots. It is also called a line plot.
A frequency table is a table that keeps a tally of how often certain events occur.