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Draw Frequency Polygons for Each of the Following Frequency Distribution: (A) Using Histogram (B) Without Using Histogram - Mathematics

Sum

Draw frequency polygons for each of the following frequency distribution: 

(a) using histogram

(b) without using histogram

C.I

10 - 30

30 - 50

50 - 70 70 - 90 90 - 110 110 - 130 130 - 150
ƒ  4 7 5 9 5 6 4
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Solution

using histogram

C.I ƒ 
10 - 30 4
30 - 50 7
50 - 70 5
70 - 90 9
90 - 110 5
110 - 130 6
130 - 150 4

Steps:

    1. Draw a histogram for the given data.
    2. Mark the mid-point at the top of each rectangle of the histogram drawn.
    3. Also, mark the mid-point of the immediately lower class-interval and mid-point of the immediately higher class-interval.
    4. Join the consecutive mid-points marked by straight lines to obtain the required frequency polygon. 

Without using Histogram:

Steps: 

  1. Find the class-mark (mid-value) of each given class-interval.
    classmark = mid-value = `" Upper limit + Lower  limit"/2`
  2. On a graph paper, mark class-marks along X-axis and frequencies along Y-axis.
  3. On this graph paper, mark points taking values of class-marks along the X-axis and the values of their corresponding frequencies along Y-axis.

  4. Draw line segments joining the consecutive points marked in step (3) above.
    C.I. Class-mark f
    -10 - 10 0 0
    10 - 30 20 4
    30 - 50 40 7
    50 - 70 60 5
    70 - 90 80 9
    90 - 110 100 5
    110 - 130 120 6
    130 - 150 140 4
    150 - 170 160 0



Concept: Graphical Representation of Data
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APPEARS IN

Selina Concise Mathematics Class 9 ICSE
Chapter 18 Statistics
Exercise 18 (B) | Q 5.1 | Page 233
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