Draw a frequency polygon for the following frequency distribution.
CI
0−10
10−20
20−30
30−40
40−50
50−60
60−70
70−80
f
12
18
6
10
8
25
22
4
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Solution
Construct a histogram for the given data. Mark the mid point of the tops of rectangles of histogram and join these points by line segments. To complete the polygon, mark two classes (−10 to 0) and (80 to 90). Join the end point of the line segments to the mid points of these two classes. The curve so obtained is a frequency polygon.