A person with a mass of 52 kg runs with a speed of 6.8 m/s jumps onto the outer rim of a merry-go-round. The merry-go-round has a radius of 1.5 m and can be modeled as a large disk. The merry-go-round was initially at rest before the person jumped onto it and rotates at 1.3 rad/s immediately after the person jumps on. What is the mass (in kg) of the merry-go-round?