${\text{V}}_{\text{wody}}=30{\text{cm}}^3$  

${\text{V}}_{\text{wody+kamienia}}=35{\text{cm}}^3$ ${\text{V}}_{\text{wody+kamienia}}=35{\text{cm}}^3$  

${\text{V}}_{\text{kamienia}}={\text{V}}_{\text{wody+kamienia}}-{\text{V}}_{\text{wody}}=5{\text{cm}}^3$  

${\text{m}}_{\text{kamienia}}=13,2\text{g}$  

${\rho }_{\text{kamienia}}=\frac{{\text{m}}_{\text{kamienia}}}{{\text{V}}_{\text{kamienia}}}=\frac{13,2\text{g}}{5{\text{cm}}^3}$  

${\rho }_{\text{kamienia}}=2,64\frac{\text{g}}{{\text{cm}}^3}$