A boxcar of mass 5.32 x 10^4 kg is rolling south at 3.49 m/s when it collides and couples with another boxcar that is rolling north at 5.12 m/s. The velocity of the coupled boxcars after collision is 1.32 m/s north. Find the mass of the boxcar that was initially rolling north. Take north as positive and express your result to three significant digits.