| Height in cm | 70-75 | 75-80 | 80-85 | 85-90 | 90-95 | 95-100 | 100-105 | 105-110 | 110-115 |
| No. of children | 3 | 4 | 7 | 7 | 15 | 9 | 6 | 6 | 3 |
| Height in cms. | Mid values xi | fi | $u = \frac{{x - 92.5}}{5}$ | fu | fu2 |
| 70-75 | 72.5 | 3 | - 4 | - 12 | 48 |
| 75-80 | 77.5 | 4 | - 3 | - 12 | 36 |
| 80-85 | 82.5 | 7 | - 2 | - 14 | 28 |
| 85-90 | 87.5 | 7 | - 1 | - 7 | 7 |
| 90-95 | 92.5 | 15 | 0 | 0 | 0 |
| 95-100 | 97.5 | 9 | 1 | 9 | 9 |
| 100-105 | 102.5 | 6 | 2 | 12 | 24 |
| 105-110 | 107.5 | 6 | 3 | 18 | 54 |
| 110-115 | 112.5 | 3 | 4 | 12 | 48 |
| 60 | 6 | 254 |
Mean $(\bar x) = A + \frac{{\Sigma fu}}{N} \times h = 92.5 + \frac{6}{{60}} \times 5$ = 92.5 + 0.5 = 93
Variance $({\sigma ^2}) = \frac{{{h^2}}}{{{N^2}}}[N\Sigma f{u^2} - {(\Sigma fu)^2}]$
$= \frac{{{{(5)}^2}}}{{{{(60)}^2}}}[60 \times 254 - {(6)^2}]$
$ = \frac{{25}}{{3600}}[15240 - 36] = \frac{{25}}{{3600}} \times 15204 = 105.58$
Standard deviation $(\sigma ) = \sqrt {105.58} = 10.27$
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