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Calculate the mean deviation about median age for the age distribution of 100 persons given below: Age Number 16 - 20 5 21 - 25 6 26 - 30 12 31 - 35 14 36 - 40 26 41 - 45 12 46 - 50 16 51 - 55 9

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Question

Calculate the mean deviation about median age for the age distribution of 100 persons given below:

Age Number
16 - 20 5
21 - 25 6
26 - 30 12
31 - 35 14
36 - 40 26
41 - 45 12
46 - 50 16
51 - 55 9
Sum
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Solution

Converting the given data into continuous frequency distribution:

Modified Class Mid-point fi c.f. |xi − M| fi |xi − M|
15.5 - 20.5 5 5 18 20 100
20.5 - 25.5 6 11 23 15 30
25.5 - 30.5 12 23 28 10 120
30.5 - 35.5 14 37 33 5 70
35.5 - 40.5 26 63 38 0 0
40.5 - 45.5 12 75 43 5 60
45.5 - 50.5 16 91 48 10 160
50.5 - 55.5 9 100 53 15 135
Sum - 100 - - 735

Median Age: 35.5 − 40.5, l = 35.5, h = 5, C = 37, f = 26

∴ Median = `"l" + ("N"/2 -"c")/"f" xx "h"`

= `35.5 + ((0 - 37)/26) xx 5`

= `35.5 + 13/26 xx 5`

= 35.5 + 2.5 

= 38

Mean Deviation (M) = `(sum"f"_"i" |"x"_"i" - "M"|)/"N"`

= `735/100`

= 7.35

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Chapter 13: Statistics - EXERCISE 13.1 [Page 271]

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NCERT Mathematics [English] Class 11
Chapter 13 Statistics
EXERCISE 13.1 | Q 12. | Page 271

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