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Home > Statistical Methods calculators > Population Skewness, Kurtosis for grouped data calculator
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Solution
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Solution provided by AtoZmath.com
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Population Skewness, Kurtosis for grouped data calculator
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1. Calculate the mean and standard deviation for the following distribution
| X |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| f |
3 |
6 |
9 |
13 |
8 |
5 |
4 |
2. Calculate the mean and standard deviation for the following distribution
| Class |
50-55 |
45-50 |
40-45 |
35-40 |
30-35 |
35-30 |
20-25 |
| f |
25 |
30 |
40 |
45 |
80 |
110 |
170 |
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Example1. Calculate Population Skewness from the following grouped data Solution:Skewness :Mean `bar x=(sum f x)/n` `=55/25` `=2.2` `x` `(2)` | `f` `(3)` | `f*x` `(4)=(2)xx(3)` | `(x-bar x)` `(5)` | `f*(x-bar x)^2` `(6)=(3)xx(5)` | `f*(x-bar x)^3` `(7)=(5)xx(6)` | | 0 | 1 | 0 | -2.2 | 4.84 | -10.648 | | 1 | 5 | 5 | -1.2 | 7.2 | -8.64 | | 2 | 10 | 20 | -0.2 | 0.4 | -0.08 | | 3 | 6 | 18 | 0.8 | 3.84 | 3.072 | | 4 | 3 | 12 | 1.8 | 9.72 | 17.496 | | --- | --- | --- | --- | --- | --- | | -- | `n=25` | `sum f*x=55` | `-- | `=26` | `=1.2` |
Population Standard deviation `sigma = sqrt((sum (x - bar x)^2)/n)` `=sqrt(26/25)` `=sqrt(1.04)` `=1.0198`
Population Skewness `= (sum(x - bar x)^3)/(n*S^3)` `=1.2/(25*(1.0198)^3)` `=1.2/(25*1.0606)` `=0.0453`
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