The scattering and absorption cross-sections of \({ }^{12} \mathrm{C}\) for thermal neutrons are \(5.56 b\) and \(0.0035 b\), respectively. Calculate the transport mean free path of neutrons if the atom density of \({ }^{12} \mathrm{C}\) in the medium is \(2.5 \times 10^{22}\) atoms / cc.