The ratios of inclusive electron scattering cross sections of 4 He, 12 C, and 56 Fe to 3 He have been measured for the first time. It is shown that these ratios are independent of x B at Q 2 Ͼ1.4 GeV 2 for x B Ͼ1.5, where the inclusive cross section depends primarily on the high momentum components of the nuclear wave function. The observed scaling shows that the momentum distributions at high-momenta have the same shape for all nuclei and differ only by a scale factor. The observed onset of the scaling at Q 2 Ͼ1.4 GeV 2 and x B Ͼ1.5 is consistent with the kinematical expectation that two-nucleon short range correlations ͑SRC͒ dominate the nuclear wave function at p m տ300 MeV/c. The values of these ratios in the scaling region can be related to the relative probabilities of SRC in nuclei with Aу3. Our data, combined with calculations and other measurements of the 3 He/deuterium ratio, demonstrate that for nuclei with Aу12 these probabilities are 4.9-5.9 times larger than in deuterium, while for 4 He it is larger by a factor of about 3.8.