[tex]dane:\\V = 750 \ cm^{3} = 0,00075 \ m^{3}\\F_{w} = 6,9 \ N\\g = 10\frac{N}{kg}\\szukane:\\d = ?\\\\Rozwiazanie\\\\F_{w} = d\cdot g\cdot V \ \ /:(V\cdot g)\\\\d = \frac{F_{w}}{V\cdot g}\\\\d = \frac{6,9 \ N}{0,00075m^{3}\cdot10\frac{N}{kg}}=920\frac{kg}{m^{3}}\\\\Odp. \ D.[/tex]