Draw a frequency polygon from the following data, giving the age of doctors working in C.G.H.S. in a city.

Explanation

The required frequency polygon is shown in the following figure:
Steps:
1. Draw a histogram for the given data.
2. Mark the mid-point at the top of each rectangle of the histogram drawn.
3. Also, mark the mid-point of the immediately lower class-interval (in the given example, the immediately lower class-interval is (20-25) and mid-point of the immediately higher class-interval (in the given example the immediate upper class-interval is 50-55)
4. Join the consecutive mid-points marked by straight lines to obtain the required frequency polygon.