Histogram
A histogram is a type of bar graph that displays frequency data organized into equal-width intervals, with no gaps between the bars. For example, test scores can be grouped as 80-84, 85-89, 90-94, and 95-100, with the height of each bar representing the number of students in that range. In Grade 7 Saxon Math Course 2, Chapter 5, students learn to read and construct histograms as part of data analysis. Unlike bar graphs, which compare distinct categories, histograms show the distribution of continuous data.
Key Concepts
Property A histogram is a special type of bar graph that displays data in equal sized intervals. There are no spaces between the bars.
Examples Test scores from 80 100 are grouped: 80 84 (5 students), 85 89 (12 students), 90 94 (8 students), 95 100 (3 students). The tallest bar is for the 85 89 interval. A histogram shows the ages of visitors at a park: 15 people are aged 0 9, 25 are 10 19, 30 are 20 29, and 10 are 30 39. A histogram displays monthly rainfall. January: 0 2 inches, February: 0 2 inches, March: 2 4 inches, April: 4 6 inches. The bars show a trend of increasing rainfall.
Explanation Think of a histogram as a city skyline where each building represents a group of data, like test scores. The buildings have no gaps because the data intervals are continuous. The taller the building, the more data points, or 'people,' are inside that score range. It's a quick way to see where most of the action is happening!
Common Questions
What is a histogram in math?
A histogram is a bar graph that shows the frequency of data values within equal-sized intervals. The bars touch each other because the intervals are continuous with no gaps.
How is a histogram different from a bar graph?
A bar graph compares distinct categories with gaps between bars. A histogram shows continuous numerical data grouped into intervals, so the bars touch each other.
How do you read a histogram?
Find the interval on the horizontal axis, then read the height of the bar on the vertical axis to determine the frequency (count) for that interval.
How do you construct a histogram?
Create equal-width intervals covering all data values, count how many data points fall in each interval, then draw a connected bar for each interval with height equal to the frequency.
When do 7th graders learn about histograms?
Saxon Math, Course 2, Chapter 5 covers histograms as part of the Grade 7 statistics and data display unit.
What can you determine from a histogram?
A histogram shows the distribution shape (symmetric, skewed), identifies where most values cluster, and reveals any gaps or outliers in the data set.