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In Question 1 (V) Find the Number of Observations Lying Between ¯ X − M.D. and ¯ X + M.D, Where M.D. is the Mean Deviation from the Mean.

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Question

In 38, 70, 48, 34, 63, 42, 55, 44, 53, 47 find the number of observations lying between

\[\bar { X } \]  − M.D. and

\[\bar { X } \]   + M.D, where M.D. is the mean deviation from the mean.

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Solution

 Let  \[\bar{x}\]  be the mean of the data set.

\[\bar{ x } = \frac{38 + 70 + 48 + 34 + 63 + 42 + 55 + 44 + 53 + 47}{10} = 49 . 4\]

\[x_i\]
 
\[\left| d_i \right| = \left| x_i - 49 . 4 \right|\]
38 11.4
70 20.6
48 1.4
34 15.4
63 13.6
42 7.4
55 5.6
44 5.4
53 3.6
47 2.4
Total 86.8

\[MD = \frac{1}{10} \times 86 . 6 = 8 . 68\]

\[\bar{ x } - MD = 49 . 4 - 8 . 68 = 40 . 72\]

\[\text{ and } \bar { x  } + MD = 49 . 4 + 8 . 68 = 58 . 08\]

There are 6 observations between 40.72 and 58.08.

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Chapter 32: Statistics - Exercise 32.1 [Page 6]

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R.D. Sharma Mathematics [English] Class 11
Chapter 32 Statistics
Exercise 32.1 | Q 5.3 | Page 6

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