A boy of mass mboy stands at the edge of a merry-go-round of radius R = 3.9 m and mass mmgr, and both are initially at rest. The boy then walks along the edge of the merry-go-round. After walking a distance of 17 m relative to the merry-go-round, the boy finds that the merry-go-round has rotated through an angle of 50°. Find the ratio of mboy to mmgr.