What is a graph on which three or more scales are arranged so that a straight line drawn through values on any two will cross the third at a corresponding value?

• A. Nomograph
• B. Bar Chart
• C. Histogram
• D. Scatter Plot

Answer: (A)

A nomograph is a graphical calculator that uses three or more scales laid out so that a straight line drawn through values on any two scales will cross the third scale at the corresponding value. You use it by aligning a straightedge through the known values on two scales; where that line hits the third scale gives the computed result without doing arithmetic. This geometric setup lets you solve relationships quickly and visually, and it’s especially common in engineering and navigation for rapid unit conversions and functional calculations. Bar charts and histograms are simple representations of data with bars and distributions, not interconnected scales for computation, while a scatter plot shows relationships between two variables and may have a line of best fit—but it doesn’t involve three or more aligned scales whose intersection yields a value.