$\text{I.}\frac{1}{9}+\frac{2}{9}+\frac{3}{9}+\frac{4}{9}+\frac{5}{9}+\frac{6}{9}+\frac{7}{9}+\frac{8}{9}=\underline{4}$  

$\frac{1}{2\cdot 5+1}+\frac{2}{2\cdot 5+1}+\frac{3}{11}+\frac{4}{11}+\frac{5}{11}+\frac{6}{11}+\frac{7}{11}+\frac{8}{11}+\frac{9}{11}+\frac{10}{11}=\underline{5}$ $\frac{1}{2\cdot 5+1}+\frac{2}{2\cdot 5+1}+\frac{3}{11}+\frac{4}{11}+\frac{5}{11}+\frac{6}{11}+\frac{7}{11}+\frac{8}{11}+\frac{9}{11}+\frac{10}{11}=\underline{5}$   

 

$\text{II.}\underline{\text{C.}}$  

$\text{Uzusadnienie na przykładzie:}$

${}_n{}_n$    

${}^{\downarrow }{}^{\downarrow }$     

$\frac{1}{2\cdot 4+1}+\frac{2}{9}+\frac{3}{9}+\frac{4}{9}+\frac{5}{9}+\frac{6}{9}+\frac{7}{9}+\frac{2\cdot 4}{9}=4$  

${}_{\uparrow }$  

${}^n$