<span>Выборочное среднее:
</span>
![\overline{x}\displaystyle= \frac{\displaystyle\sum_{i}x_in_i}{\displaystyle\sum_in_i} = \frac{7.6\cdot6+8\cdot8+8.4\cdot16+8.8\cdot50+9.2\cdot 30+9.6\cdot15+}{6+8+16+50+30+15+7+5} \\ \\ \frac{10\cdot7+10.4\cdot5}{} = \frac{1226}{137}](https://tex.z-dn.net/?f=%5Coverline%7Bx%7D%5Cdisplaystyle%3D+%5Cfrac%7B%5Cdisplaystyle%5Csum_%7Bi%7Dx_in_i%7D%7B%5Cdisplaystyle%5Csum_in_i%7D+%3D+%5Cfrac%7B7.6%5Ccdot6%2B8%5Ccdot8%2B8.4%5Ccdot16%2B8.8%5Ccdot50%2B9.2%5Ccdot+30%2B9.6%5Ccdot15%2B%7D%7B6%2B8%2B16%2B50%2B30%2B15%2B7%2B5%7D+%5C%5C+%5C%5C++%5Cfrac%7B10%5Ccdot7%2B10.4%5Ccdot5%7D%7B%7D+%3D+%5Cfrac%7B1226%7D%7B137%7D+)
<span>Выборочная дисперсия равна
</span>
![\widehat{s}^2=\overline{x^2}-\overline{x}^2=\displaystyle \frac{\displaystyle \sum_in_ix_i^2}{\displaystyle \sum_in_i} -\overline{x}^2= \frac{275548}{3425} - \frac{1226^2}{137^2}= \frac{173176}{469225}](https://tex.z-dn.net/?f=%5Cwidehat%7Bs%7D%5E2%3D%5Coverline%7Bx%5E2%7D-%5Coverline%7Bx%7D%5E2%3D%5Cdisplaystyle+%5Cfrac%7B%5Cdisplaystyle+%5Csum_in_ix_i%5E2%7D%7B%5Cdisplaystyle+%5Csum_in_i%7D+-%5Coverline%7Bx%7D%5E2%3D+%5Cfrac%7B275548%7D%7B3425%7D+-+%5Cfrac%7B1226%5E2%7D%7B137%5E2%7D%3D++%5Cfrac%7B173176%7D%7B469225%7D+)
<span>Выборочное среднее квадратическое отклонение равно
</span>
![\widehat{s}= \sqrt{\widehat{s}^2} =\displaystyle \sqrt{\frac{173176}{469225}} = \frac{ \sqrt{173176} }{685}](https://tex.z-dn.net/?f=%5Cwidehat%7Bs%7D%3D+%5Csqrt%7B%5Cwidehat%7Bs%7D%5E2%7D+%3D%5Cdisplaystyle++%5Csqrt%7B%5Cfrac%7B173176%7D%7B469225%7D%7D+%3D+%5Cfrac%7B+%5Csqrt%7B173176%7D+%7D%7B685%7D+)
(12ⁿ-3ⁿ)/(2ⁿ+1)=3ⁿ*(4ⁿ-1)/(2ⁿ+1)=3ⁿ*(2²ⁿ-1)/(2ⁿ+1)=
=3ⁿ*(2ⁿ+1)*(2ⁿ-1)/(2ⁿ+1)=3ⁿ*(2ⁿ-1).
7(х-2у) - числитель
х(а-в)-2у(а-в)=(а-в)(х-2у) - знаменатель
сокращаем на (х-2у)
=7/а-в
Полное реш. внутри
Надеюсь, помог
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(6.8*10⁻³)(2*10⁻³)=6.8*2*10⁻³⁻³ = 13.6*10⁻⁶ = 1.36*10⁻⁵