Histograms

The data used here is again the weights of 50 high school students used in the section, Summarizing Data with Tables.

Below is the histogram for this data that uses the same classes that were used in the section, Summarizing Data with Tables.

The horizontal axis is weight in pounds while the vertical axis gives the frequency of each class. Note that the side of each bar occurs at a class boundary. The height of each bar corresponds to the frequency of the class.

It is possible to make a histogram for a relative frequency table. Below is the relative frequency histogram for this data.

The horizontal axis is weight in pounds while the vertical axis gives the relative frequency of each class. The edge of each bar occurs at a class boundary. The height of each bar corresponds to the relative frequency of the class.

It is possible to make a graph corresponding to the cumulative frequency table. This graph (not mentioned in your text) is called an ogive . Below is the graph for this data.

This graph is a series of connected line segments. In order to see how the line segments are constructed we need to review some of the data. Recall that for this data there were no students who weighed less than 82 pounds, two who weighed less than 104, and seven who were less than 126 pounds. Using this information, we connect the pairs (82,0) and (104,2) to get the first line segment. The second line segment connects (104,2) and (126,7). The rest of the graph is completed using the rest of the information in the cumulative frequency table.