(I) Steps to Draw Frequency Polygon in Discrete Series

The steps required to construct a frequency polygon in the case of discrete series are: 

1. Write the values of the given variable (say, X) on the X-axis and the corresponding frequencies on the Y-axis.
2. Draw a straight line connecting the points of the various frequencies.
3. Extend the figure to the base (base-line) at both ends by connecting the extreme points (first and last point) to the two hypothetical values of the variable (prior to the first value of the variable and after the last value of the variable), both of which are assumed to have zero frequency.

Example of Frequency Polygon in Discrete Series: 

The following data shows the number of shops on 70 streets in a city. Construct a frequency polygon for the same.

Solution:

The discrete frequency distribution applies in this case. The number of rooms will be plotted on the X-axis, while the number of houses will be plotted on the Y-axis. A frequency polygon is created by joining the obtained points with a straight line.