In a city, the weekly observations made in a study on the cost of living index are given in the following table :

Cost of living index	Number of weeks
140 - 150	5
150 - 160	10
160 - 170	20
170 - 180	9
180 - 190	6
190 - 200	2

Draw a frequency polygon for the data given above.

Frequency distribution table :

Steps to draw frequency polygon :

1. Since, the scale on x-axis starts at 130, a kink is shown near the origin on x-axis to indicate that the graph is drawn to scale beginning at 130.

2. Take 2 cm along x-axis = 10 units (cost of living index).

3. Take 2 cm along y-axis = 5 weeks.

4. Find the mid-points of class-intervals.

5. Find points corresponding to given frequencies of classes and the mid-points of class-intervals, and plot them.

6. Join consecutive points by line segments.

7. Join first end point with mid-point of class 130 - 140 with zero frequency and join the other end with mid-point of class 200 - 210 with zero frequency.

The required frequency polygon is shown alongside.