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Question
Find the mean deviation about the mean for the data.
| xi | 5 | 10 | 15 | 20 | 25 |
| fi | 7 | 4 | 6 | 3 | 5 |
Solution
| xi | fi | fi xi | `|"x"_"i" - overline "x"|` | `"f"_"i"|"x"_"i" - overline "x"|` |
| 5 | 7 | 35 | 9 | 63 |
| 10 | 4 | 40 | 4 | 16 |
| 15 | 6 | 90 | 1 | 6 |
| 20 | 3 | 60 | 6 | 18 |
| 25 | 5 | 125 | 11 | 55 |
| Sum | 25 | 350 | - | 158 |
`overline "x" = (sum"f"_"i""x"_"i")/(sum"f"_"i")`
= `350/25`
= 14
Mean Deviation = `(sum"f"_"i" |"x"_"i" - overline"x"|)/"N"`
= `158/25`
= 6.32
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