To draw histograms
for classes of equal
Answers
Answer:
intervals as bases and the corresponding frequencies as heights. There being no gap between any two consecutive rectangles.
Histogram is commonly used to show frequency distribution.
Procedure
1. Firstly, collect the data from daily life such as weights/heights of children in a class, then make a frequency distribution table.
Case I For classes of equal widths,
Class a-b b-c c -d d -e e-f
Frequency f1 f2 f3 f4 f5
Case II For classes of varying widths,
Here, d – f = 2(a-b)
Class a-b
(width x) b-c
(width x) c-d
(width x)
d-f
(width 2x)
Frequency f1 f2 f3 f4
Modified frequency f1 f2 f3 F’ = \frac { { f }_{ 4 } }{ 2 }
2. Take a graph paper having dimensions (20cm x 20cm) and paste it on a piece of cardboard sheet.
3. Now, draw two perpendicular axes X’OX and Y’OY on the graph paper, (see Fig. 32.1)
4. At equal distances, mark classes on X-axis and frequency Y-axis, (see Fig. 32.1)
ncert-class-9-maths-lab-manual-draw-histograms-classes-equal-widths-varying-widths-1
5. Draw rectangles of equal widths and heights f1, f2, f3, f4 and f5 on intervals (a-b), (b-c), (c-d), (d-e) and (e-f), respectively, (see Fig. 32.2)
ncert-class-9-maths-lab-manual-draw-histograms-classes-equal-widths-varying-widths-2
6. Draw rectangles of heights f1, f2, f3 and F’ on intervals (a-b), (b-c), (c-d) and (d-f) respectively, (see Fig. 32.3)
ncert-class-9-maths-lab-manual-draw-histograms-classes-equal-widths-varying-widths-3
Answer:
A histogram consists of rectangle whose area is proportional to the frequency of a variable ad whose with is equal to the class interval.
Step-by-step explanation:
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