Question

A playground merry-go-round (which can be modeled as a disk) has a 3.4 m diameter, a mass of 240 kg and is rotating at 22.5 rpm. A 35 kg child running at 6.0 m/s, tangent to and in the same direction as the merry-go-round is turning, jumps on the outer edge. Ignoring any friction, what is the angular velocity in rpm after the child jumps on?