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Find the mean deviation about the median of the following distribution: Marks obtained 10 11 12 14 15 No. of students 2 3 8 3 4

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प्रश्न

Find the mean deviation about the median of the following distribution:

Marks obtained 10 11 12 14 15
No. of students 2 3 8 3 4
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योग
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उत्तर

Marks
obtained
`f_i` `c.f.` `d_i = |x_i - Med|` `f_i d_i`
10 2 2 2 4
11 3 5 1 3
12 8 13 0 0
14 3 16 2 6
15 4 20 3 12
Total 20     25

Here `sumf_i` = N = 20 and `sumf_i d_i` = 25

Median = `1/2[(N/2)^"th"  "observation" + (N/2 + 1)^"th"  "observation"]`

= `1/2[(20/2)^"th" "observation" + (20/2 + 1)^"th"  "observation"]`

= `1/2[10^"th"  "observation" + 11^"th"  "observation"]`

= `1/2[12 + 12]`

∴ Median = 12

∴ M.D. = `(sumf_i d_i)/(sum f_i)`

= `25/50`

= 1.25

Hence, the required M.D. = 1.25

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अध्याय 15: Statistics - Exercise [पृष्ठ २७८]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 11
अध्याय 15 Statistics
Exercise | Q 2 | पृष्ठ २७८

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