Ricardo, of mass 74 kg, and Carmelita, who is lighter, are enjoying Lake Merced at dusk in a 33 kg canoe. When the canoe is at rest in the placid water, they exchange seats, which are 3.0 m apart and symmetrically located with respect to the canoe's center. Ricardo notices that the canoe moves 52.6 cm horizontally relative to a pier post during the exchange and calculates Carmelita's mass. What is it?