Question

A 3.6 diameter merry-go-round is rotating freely with an angular velocity of 0.73 . Its total moment of inertia is 1600 . Four people standing on the ground, each of mass 60 , suddenly step onto the edge of the merry-go-round.What is the angular velocity of the merry-go-round now?What if the people were on it initially and then jumped off in a radial direction (relative to the merry-go-round)?