A playground merry-go-round of radius R = 2.00 m has a moment of inertia I = 250 kg.m2 and is rotating at 10.0 rev/min about a frictionless, vertical axle. Facing the axle, a 25.0-kg child hops onto the merry-go-round and manages to sit down on the edge. The new angular speed of the merry-go-round is