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Question
Find the mean deviation about the mean for the data.
4, 7, 8, 9, 10, 12, 13, 17
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Solution
Arithmetic mean `overline x = (4 + 7 + 8 + 9 + 10 + 12 + 13 + 17)/8`
= `80/8`
= 10
`sum |x_i - overline x| = |4 - 10| + |7 - 10| + |8 - 10| + |9 - 10| + |10 - 10| + |12 - 10| + |13 - 10| + |17 - 10|`
= 6 + 3 + 2 + 1 + 0 + 2 + 3 + 7
= 24
∴ Mean deviation about the mean MD `(overline x) = (sum |x_i - overline x|)/n`
= `24/8`
= 3
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