Mathematics
The heights of boys in a school are given below :
| Height (in cm) | Number of boys |
|---|---|
| 140 - 145 | 24 |
| 145 - 150 | 32 |
| 150 - 155 | 16 |
| 155 - 160 | 20 |
| 160 - 165 | 44 |
Draw a frequency polygon to represent the above data.
Answer
Frequency distribution table :
| Height (in cm) | Class mark | Frequency |
|---|---|---|
| 140 - 145 | 142.5 | 24 |
| 145 - 150 | 147.5 | 32 |
| 150 - 155 | 152.5 | 16 |
| 155 - 160 | 157.5 | 20 |
| 160 - 165 | 162.5 | 44 |
Steps to draw frequency polygon :
Take 2 cm along x-axis = 5 cm.
Take 2 cm along y-axis = 10 boys.
Find the mid-point of class intervals.
A kink is drawn near x-axis to show that the scale begins at 140.
Find points corresponding to given frequencies of classes and the mid-points of class-intervals, and plot them.
Join consecutive points by line segments.
Join first end point with mid-point of class 135 - 140 with zero frequency and join the other end with mid-point of class 165 - 170 with zero frequency.
The required frequency polygon is shown below :
Related Questions
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