Answer
2.70 $g/cm^{3}$
Work Step by Step
Volume = 4.77 L = $4.77\times10^{3}mL = 4.77\times10^{3} cm^{3}$ $(1 mL = 1 cm^{3})$
Mass = $12.88kg = 12.88\times10^{3}g$
Density = $\frac{Mass}{Volume}=\frac{12.88\times10^{3}g}{4.77\times10^{3} cm^{3}}$ = $2.70 g/cm^{3}$