Ricky, mass 95 kg, and Cathy, who is lighter, are enjoying Lake Mendota at dusk in a 20 kg canoe that is 3.0 m long.When the canoe is at rest in placid water, they exchange seats, which are at the ends of the canoe. Ricky notices the canoe moved 30 cm relative to a submerged rock during the exchange and uses that to calculate Cathy's mass. What is Cathy's mass?