information graphically or information given certain conditions. They often utilize values shown on the x and y axes that can be projected up and across to arrive at a specific result. Also, when data is entered into a computer database, software programs can create a variety of different bar graphs, pie charts, and so forth, to graphically represent that data.

**Reading and Interpreting Graphs and Charts**

When interpreting information shown on graphs and charts, it is extremely important that all the notes and legend information be carefully understood in order to eliminate any misinterpretation of the information presented.

**Nomograms**

A nomogram is a graph that usually consists of three sets of data. Knowledge of any two sets of data enables the interpreter to obtain the value for the third unknown corresponding value. One type of nomogram consists of three parallel scales graduated for different variables so that when a straight edge connects any two values, the third can be read directly. Other types may use values on the x and y axes of a graph with the third corresponding value determined by the intersection of the x and y values with one of a series of curved lines. Figure 2-31 is an example of a nomogram that shows the relationship between aviation fuels, specific weight, and temperature.