$${d^* = \frac{m_c}{\rho c_\text{õ} A_\text{auto}} = \frac{1000\, \mathrm{kg}}{1,3 \, \mathrm{kg/m^3} \times \frac{1}{3} \times 3\, \mathrm{m^2}} = 750\, \mathrm{m}}$$