$16+9=25$  

 

$\text{a)}$  

$6:40\%\cdot 25=\frac{40}{100}\cdot 25=\frac{2}{5}\cdot 25=2\cdot 5=10$  

$1:20\%\cdot 25=\frac{20}{100}\cdot 25=\frac{1}{5}\cdot 25=5$  

$5:16\%\cdot 25=\frac{16}{100}\cdot 25=$   $\frac{4}{25}\cdot 25=4$  

$2:12\%\cdot 25=\frac{12}{100}\cdot 25=\frac{3}{25}\cdot 25=3$  

$4:8\%\cdot 25=\frac{8}{100}\cdot 25=\frac{2}{25}\cdot 25=2$  

$3:4\%\cdot 25=\frac{4}{100}\cdot 25=\frac{1}{25}\cdot 25=1$   

$\text{stopienˊ}$	$1$	$2$	$3$	$4$	$5$	$6$
$\text{liczba ucznioˊw}$	$5$	$3$	$1$	$2$	$4$	$10$

 

$\text{b)}$  

$\text{sˊrednia}=\frac{1\cdot 5+2\cdot 3+3\cdot 1+4\cdot 2+5\cdot 4+6\cdot 10}{25}=$  

$=\frac{5+6+3+8+20+60}{25}=$   $\frac{102}{25}=4\frac{2}{25}=4,08$  

$\text{moda}=6$  

$\text{mediana}=5$     $\text{(trzynasty wynik)}$