Answer
1.26 $g/cm^{3}$
Work Step by Step
Volume = 2.50 L = $2.50\times10^{3}mL = 2.50\times10^{3} cm^{3}$ $(1 mL = 1 cm^{3})$
Mass = $3.15\times10^{3}g$
Density = $\frac{Mass}{Volume}=\frac{3.15\times10^{3}g}{2.50\times10^{3} cm^{3}}$ = $1.26 g/cm^{3}$