[tex]\boxed{\begin{array}{l}\tt 9)\\\underline{\rm c\acute alculo~da~m\acute edia\!:}\\\sf\overline{m}=\dfrac{7+7,5+6+5,5+8}{5}=\dfrac{34}{5}=6,8.\\\underline{\rm c\acute alculo~dos~desvios\!:}\\\sf7-6,8=0,2\\\sf7,5-6,8=0,7\\\sf6-6,8=-0,8\\\sf5,5-6,8=-1,3\\\sf 8-6,8=1,2\\\underline{\rm soma~dos~quadrados~dos~desvios\!:} \\\sf s^2=\dfrac{0,2^2+0,7^2+(-0,8)^2+(-1,3)^2+1,2^2}{5}\\\sf s^2=\dfrac{0,04+0,49+0,64+1,69+1,44}{5}=\dfrac{4,3}{5}\approx0,8\\\bf desvio~padr\tilde ao\!:\\\sf s=\sqrt{s^2}\\\sf s=\sqrt{0,8}\\\sf s\approx0,93\end{array}}[/tex]
[tex]\boxed{\begin{array}{l}\tt 10)\\\sf \dfrac{0,2+0,7+|-0,8|+|-1,3|+1,2}{5}=\dfrac{4,2}{5}\approx0,8\end{array}}[/tex]
