Page 4 - Lesson note-4- Ch 14 Statistics( Frequency Polygon)
P. 4
Frequency polygons can also be drawn independently without drawing histograms.
Example 3: In a study of diabetic patients in a village, the following observations
were noted.
Age in years Number of
patients
10-20 2
20-30 5
30-40 12
40-50 19
50-60 9
60-70 4
Represent the above data by a frequency polygon.
Solution:
We know that Class mark of a class interval = ( + )
2
Age in years Class mark Number of
patients
0-10 5 0
10-20 15 2
20-30 25 5
30-40 35 12
40-50 45 19
50-60 55 9
60-70 65 4
70-80 75 0
By taking imaginary class intervals 0 – 10 and 70 – 80 with frequency 0 plot the points
by taking class marks on X-axis and frequencies on the Y-axis.
