6.3 Histograms with Class Interval of the Same Size

6.3 Histograms
 
(A) Draw a histogram based on the frequency table of a grouped data
 
1. A histogram is a graphical representation of a frequency distribution.
2. A histogram consists of vertical rectangular bars without any spacing
    between them.
3. Steps for drawing a histogram
(a) Determine the lower boundaries and upper boundaries for each class 
      interval.
(b) Choose suitable scales for the horizontal axis (x-axis) to represent 
      class interval and the vertical axis (y-axis) to represent frequency.
 
Example:
The following frequency table shows the radii, in cm, of different types of trees in a garden.
 
Radii (cm)
Frequency
2.0 – 2.4
7
2.5 – 2.9
5
3.0 – 3.4
10
3.5 – 3.9
2
4.0 – 4.4
6
4.5 – 4.9
4
Draw a histogram to represent the above information.

Solution:
Radii (cm)
Frequency
Lower boundary
Upper boundary
2.0 – 2.4
7
1.95
2.45
2.5 – 2.9
5
2.45
2.95
3.0 – 3.4
10
2.95
3.45
3.5 – 3.9
2
3.45
3.95
4.0 – 4.4
6
3.95
4.45
4.5 – 4.9
4
4.45
4.95



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