Compare Numbers Using a Bar Graph
A bar graph gives you an easy way to compare numbers or values. For example, the following figure shows a bar graph comparing the performance of five trainers at a fitness center.
As you can see from the caption, the graph shows how many new clients each trainer has enrolled this quarter. The advantage of such a graph is that you can see at a glance, for example, that Edna has the most new clients and Iris has the fewest. The bar graph is a good way to represent numbers that are independent of each other. For example, if Iris gets another new client, it doesn’t necessarily affect any other trainer’s performance.
Reading a bar graph is easy after you get used to it. Here are a few types of questions someone could ask about the bar graph shown in the figure:

Individual values: How many new clients does Jay have? Find the bar representing Jay’s clients and notice that he has 23 new clients.

Differences in value: How many more clients does Rita have compared with Dwayne? Notice that Rita has 20 new clients and Dwayne has 18, so she has 2 more than he does.

Totals: Together, how many clients do the three women have? Notice that the three women — Edna, Iris, and Rita — have 25, 16, and 20 new clients, respectively, so they have 61 new clients altogether.