4-68. Ponderosa Paint and Glass makes paint at three plants. It then ships the unmarked paint cans to a central warehouse. Plant A supplies 50% of the paint, and past records indicate that the paint is incorrectly mixed 10% of the time. Plant B contributes 30%, with a defective rate of 5%. Plant C supplies 20%, with paint mixed incorrectly 20% of the time. If Ponderosa guarantees its product and spent $10,000 replacing improperly mixed paint last year, how should the cost be distributed among the three plants