Question

multiple choice question
a frequency distribution table shows the number of observations for each class interval of data. how is this data plotted as a frequency polygon?
frequency is plotted on the horizontal axis and the class interval is plotted on the vertical axis.
frequency is plotted on the vertical axis and the class interval is plotted on the horizontal axis.
the cumulative proportion of observations for each class is plotted on the vertical axis and the class upper limit is plotted on the horizontal axis.
frequency is plotted on the vertical axis and the class midpoint is plotted on the horizontal axis.

Explanation:

A frequency polygon is constructed by plotting the frequency of each class on the vertical axis, and using the midpoint of each class interval on the horizontal axis to represent the class, then connecting these points with line segments. The other options are incorrect: swapping axes misrepresents the plot, cumulative proportions relate to ogives, and using class intervals directly (not midpoints) is not standard for a frequency polygon.

Answer:

Frequency is plotted on the vertical axis and the class midpoint is plotted on the horizontal axis.